How to Choose the Right Industrial Thermocouple

High temperature sensor, model TC80

The answer to the question “what kind of thermocouple?” depends on several factors relating to the process to be monitored, such as its compatibility with the media/process environment, frequency and accuracy of measurements required, and the regulatory environment in your industry.


Temperature measurement is a key parameter in manufacturing and processing operations in many industries, from refining to pharmaceuticals. Accurately monitoring the temperature helps ensure safe, efficient and optimal outcomes.

The two most common industrial temperature measurement technologies today are resistance temperature detectors (RTDs) and thermocouples. Each has its advantages and disadvantages.

Thermocouples offer relatively low cost, ruggedness, fast response time, and the ability to measure media up to 2,300°C (RTDs are suitable for use for up to only 850°C). However, thermocouples are less accurate than RTDs (their accuracy degrades over time), and their output is nonlinear. RTDs offer greater accuracy, repeatability, and stability, but they have slower response times and are more expensive than thermocouples.

Criteria for Selecting an Industrial Thermocouple

A thermocouple is almost always the measuring instrument of choice for applications above 800–900°C, but selecting the ideal industrial thermocouple also requires knowing some things about the process where the instrument will be used.

Weld-in thermowell (solid-machined), Model TW20

Weld-in thermowell (solid-machined), Model TW20

First, consider whether the thermocouple will be in direct contact with the process or if it will be integrated into a thermowell assembly. Thermowells protect the thermocouple from corrosive, fast-flowing, or extremely hot process media. Approximately 75% to 80% of industrial thermocouples installed in the oil and gas, refining, petrochemical, power generation, and pulp and paper industries today use thermowell assemblies.

The second decision is the material. A large majority of industrial thermocouple are made of stainless steel, but certain applications call for specialized alloys like Inconel 600, Hastelloy X, Monel, or the like. Note that thermocouples for high-temperature applications use specialized ceramic thermowells to insulate the metal wires in the instrument assembly.

Next, determine whether you need a traditional industrial thermocouple assembly or a flexible thermocouple sensor for use in a tight or difficult-to-reach location.

Finally, you must decide on the type of industrial thermocouple needed. Type, in this context, refers to the metal wires in the instrument used to actually measure temperature changes. Different metals have varying temperature ranges and other properties that make them suitable – or unsuitable – for use in specific applications.

Industrial Thermocouple Types

WIKA offers eight types of thermocouples. The primary criteria for deciding which one to use depend on the properties of the media the instrument will be in contact with, as well as the temperature of the application.

  • Type K NiCr-NiAl thermocouples — typically used in oxidizing or inert gas atmospheres up to 1,200°C (ASTM E230: 1,260°C).
  • Type J Fe-CuNi thermocouples — typically used in vacuum applications, oxidizing and reducing atmospheres, or inert gas atmospheres for temperature measurements up to 750°C (ASTM E230: 760°C).
  • Type N NiCrSi-NiSi thermocouples — typically used in oxidizing atmospheres, inert gas atmospheres, or dry reduction atmospheres up to 1,200°C (ASTM E230: 1260°C). Type N thermocouples are very accurate at high temperatures; they are often used instead of Type K thermocouples in applications where a longer service life and greater stability are required.
  • Type E NiCr-CuNi thermocouples — typically used in oxidizing or inert gas atmospheres up to 900°C (ASTM E230: 870°C).
  • Type T Cu-CuNi thermocouples — typically used at temperatures below 0°C with an upper temperature limit of 350°C (ASTM E230: 370 °C) in oxidizing, reducing, or inert gas atmospheres. These thermocouples are highly resistant to corrosion, even in moist atmospheres.
  • Types R, S, and B are noble-metal thermocouples that are typically used for higher-temperature applications. Types R and S are also used in some specialized applications because of their high accuracy and stability.

To find the right industrial thermocouple for your application, take a look at WIKA’s Quick Ship Guide for Electrical Measurement. Whether you use the preselected product codes for popular products or opt for the Quick Order Code Builder included in the guide, it is simple to order the exact thermocouple you need for your specific process.

Mechanical Pressure Switches: Options and Selection Criteria (Part 2)

Mech pressure meas instruments

Mechanical pressure switches are reliable and low-cost. And with the variety of options available, they meet the requirements of many different applications. This blog summarizes common features and factors to consider when selecting a mechanical pressure switch.

In a mechanical pressure switch, a diaphragm or a piston opens or closes a circuit when the pressure in the medium rises or drops to a certain value. Every time the pressure reaches the switch point, the diaphragm or piston transfers the pressure to a micro switch. The micro-switch contact snaps and generates an electrical output signal that is sent to a controller. Adjusting a pressure spring, either on-site or at the factory, presets the switch point. The hysteresis of the micro switch determines the switch-back or reset point of the pressure switch. Mechanical pressure switches do not require a power supply.

What to Take into Account When Selecting a Mechanical Pressure Switch

Mechanical pressure switches are a simple and affordable solution where single switch contacts are required. These switches perform reliably as long as they are carefully selected to meet the particular needs of the application. Here are some factors to consider include:

  • Medium and temperature — The medium and its temperature are critical when determining the material for the case, the wetted parts, and the sensor element. Mechanical pressure switches, where the case and the process connections are made of galvanized or stainless steel, work well with most applications. Nitrile butadiene rubber (NBR) is a good diaphragm material for mechanical pressure switches that work with medium temperatures and air or hydraulic oil. When the medium is water, ethylene propylene diene monomer rubber (EPDM) is better. Flourosilicone rubber (FVMQ) withstands higher temperatures.
  • Pressure — Diaphragms work well as sensor elements in vacuum and low-pressure applications. Pistons, usually made of stainless steel, are better suited for higher pressure ranges.
  • Switching function — Mechanical pressure switches can operate as normally open (NO) that close when they reach the switch point, as normally closed (NC) that open when they reach the preset point, or as change-over to another circuit upon a decreasing or increasing pressure (single pole single throw, or SPST).
  • Switch point adjustment — The switch point can be predetermined at the factory or can be adjusted on-site. An adjustable switch point is recommended for applications where system conditions, such as temperature and pressure, vary.
  • Hysteresis — Hysteresis determines when the switch resets. If the reset value is too large, the functions stays active for too long. If the reset value is too short, the function will bounce between states.
  • Other factors — Reproducibility, electrical current and voltage rating, weather protection, resistance to vibration and shock, mounting, and process connections also affect which model to use.

A carefully chosen mechanical pressure switch will have a long service life. Standard units should work for at least 1 million switching cycles. More expensive mechanical pressure switches should provide approximately 5 million switching cycles.

Starting with its standard PSM01, WIKA’s wide selection of mechanical pressure switches offer a variety of options that cover the requirements of most applications. WIKA’s experts can help you find the one that best fits your needs.

This article is a continuation of Mechanical Pressure Switches in Mobile Machine Applications.

Mechanical Pressure Switches in Mobile Machine Applications (Part 1)

Model PSM01: OEM compact pressure switch

Mobile machines work in harsh and extreme conditions. Users want pressure switches that provide reliable performance at affordable prices. Learn why mechanical pressure switches are an ideal choice for mobile machine applications.

Mobile machines in the construction, agriculture, mining, and material handling sectors, and in the military, work in very challenging environments. These machines are routinely subject to the detrimental effects of dust, water, wind, and extreme temperatures. Vibration, shock, and internal stresses – cavitation, pressure spikes, and changing loads – put a heavy burden on all components. Corrosion from chemicals, fuel, and engine and hydraulic oil are additional problems.

Mechanical pressure switches are simple, low-cost devices, built for reliability in these conditions. They provide dependable and long-lasting performance in a variety of mobile machine applications.

How Mechanical Pressure Switches Work

In a mechanical pressure switch, a diaphragm or a piston mechanically transfers the pressure of the medium to a snap action switch (micro switch). Every time the pressure in the fluid reaches a predetermined pressure — the switch point — the contact snaps, generating and sending an output electrical signal to a controller. The switch point is preset at the factory or on-site by adjusting a pressure spring. The switch resets when the pressure is no longer within the range of the switch point. The reset, or switch-back, point depends on the hysteresis of the micro switch.

Mechanical Switches in Mobile Machines

Mechanical pressure switches are a good fit for:

  • Stopping pumps and motors in mobile hydraulics. When the pressure in the fluid reaches a preset value, the switch sends a signal that stops the pump or motor, and prevents damage to the equipment.
  • Evaluating contamination in filters. The switch point is set to the pressure at which the filter becomes clogged. The switch sends a signal to the operator when the filter needs to be changed.
  • Protecting lifting equipment from overload. When the pressure in the lifting cylinder reaches a preset value, the switch is activated to prevent the cylinder from extending further.
  • Signaling the emergency brake and brake line systems. The increase in system pressure that occurs when engaging the brake triggers the switch, which sends a signal warning to the operator that the brake has been activated.

Mechanical pressure switches with galvanized or stainless steel case and wetted parts work well for most mobile machines. Different switching functions – normally open (NO), normally closed (NC), or change-over contact (single pole single throw, or SPST) – fit different applications. When selecting the appropriate mechanical pressure switch, consider adjustability of the switch point and switch hysteresis, current and voltage ratings, ingress protection, resistance to vibration and shock, and mounting and connectors. Bottom line, however, is service life and cost. A good, affordable standard unit should work for at least 1 million switching cycles. More expensive mechanical pressure switches should provide about 5 million switching cycles.

WIKA has Mechanical Pressure Switches

WIKA offers a complete line of mechanical pressure switches. The PSM01, a standard OEM mechanical pressure switch, has an on-site or at-the-factory adjustable switch point, and provides 1 million switching cycles. Other models feature adjustable hysteresis, continuous and precise adjustment of the switch point, high electrical ratings, and up to 5 million switching cycles. All WIKA’s mechanical pressure switches are compact, work well for a wide range of pressures, and have ingress protection IP67. They are vibration and shock resistant, in accordance with ISO 16750-3.

Call WIKA’s experts today to learn more about reliable and low-cost mechanical pressure switches for your mobile machines.

This series continues with Mechanical Pressure Switches: Options and Selection Criteria.

Critical Conditions Caused by SF6 Leaks, and How to Avoid Them

Model GA35 emission monitor for SF6 gas

Sulfur hexafluoride (SF6) has excellent heat transfer and dielectric characteristics, better than air and other gases, and has been used for decades as insulation and arc quencher in circuit breakers, disconnectors, and switchgear in the power transmission and distribution (T&D) sector. SF6 effectively protects T&D equipment and ensures proper operation and safety. Moreover, it is stable and nontoxic. However, SF6 leaks can harm the environment, equipment, and human health. Leaks must be detected early and fixed promptly to avoid critical conditions and costly consequences.

Effects on the Environment

SF6 is the most potent greenhouse gas known. It is 23,900 times more effective than carbon dioxide (CO2) at trapping infrared radiation in the atmosphere. A very stable compound, any leaked SF6 can last for up to 3,200 years before it is broken down by UV rays.

Effects on Equipment

SF6 leaks reduce the amount of dielectric insulation and heat transfer provided to T&D SF6-insulated equipment and can affect the equipment’s performance. Equipment that is insufficiently insulated can lose signal, malfunction, short-circuit, and—ultimately—fail completely, compromising operations and safety. Downtime and repairs or replacement of damaged equipment can be extremely costly. A 10% loss of gas decreases the dielectric strength required to handle short current faults to a point that can permanently damage insulators, shields, arcing contacts, and main contacts. Repairs to restore the equipment to proper working conditions can cost as much as $60,000, depending on the equipment and the damage. Malfunction and failure of SF6-insulated equipment can lead to damage to other parts of the network, and cause fires and extended outages. The financial and safety repercussions of these critical situations can be devastating.

Effects on People

While SF6 is nontoxic, it does displace oxygen in the air and can lead to asphyxiation—a daunting threat when working in closed spaces. The gas is odorless and colorless, and difficult to detect without special equipment. Because of its heavier weight, escaped SF6 settles in low areas and poses greater risks in low-lying spaces, such as trenches and pits, where people work with electrical equipment that uses the gas as insulation.

Another health hazard occurs when humidity seeps into the chamber. Under normal conditions, SF6 re-forms after electrical stress situations like an arc or corona. However, humidity can prevent this “self-healing” process from taking place. SF6 reacts with water and oxygen after a spark event to form toxic decomposition byproducts such as disulfur decafluoride (S2F10), which can damage lungs if inhaled.

Monitoring for SF6 Leaks

Online monitoring for SF6 leaks is a must to prevent critical conditions and to avoid associated hazards.

Model GDHT-20, transmitter with MODBUS® output

Model GDHT-20,
transmitter with MODBUS® output

Continuous online monitoring of SF6 density provides accurate and reliable information about gas conditions and possible leaks. WIKA’s GDHT-20 integrated gas transmitter measures density, pressure, humidity and temperature. Based on these measurements, it calculates density using a virial equation. Furthermore, the system constantly monitors the moisture content of a chamber and can alert technicians when conditions are ripe for the formation of toxic decomposition byproducts.

WIKA’s GA35 emission monitor has been especially designed for monitoring SF6 levels in ambient air within enclosed spaces. Its infrared sensor is not sensitive to humidity and common volatile organic compounds (VOC). The GA35 provides continuous measurements and ensures occupational safety.

WIKA offers a complete line of products for monitoring SF6. Contact WIKA’s experts today. They can tell you more about how to avoid critical conditions and costly consequences caused by SF6 leaks.

Long-Term Planning with Gayesco-WIKA Flex-R Multipoint System Enables Major Cost Savings


Temperature control is a critical factor for reactor vessels in the refining and chemicals industry. The catalysts that convert the process oil in these reactors work best in very specific temperature ranges, and too high or too low a temperature can have a noticeable impact on production, as well as on the lifespan of the expensive catalysts.

Given the importance of temperature control on refinery and petrochemical processes, industry leaders constantly seek innovative temperature measurement solutions. Gayesco-WIKA has worked closely with the refining and chemical industry for more than five decades. As a result, customized Flex-R multipoint thermocouple solutions have been installed in more than 4,000 pressure vessels worldwide.

Flex-R installations are well-known for their remarkable longevity, and the two- to three-decade lifespan of these robust systems leads to cost savings and operational synergies that can add up to tens of millions of dollars.

Long Lifetime Allows for Reliable Long-term Planning and Operational Synergies

Multipoint thermocouple, model TC96-R

Multipoint thermocouple, model TC96-R

Obviously, needing to replace an expensive multipoint temperature system only every 25–30 years leads to major cost savings. (Other multipoint systems often last only 10–15 years.) That being said, the overall cost savings with the long-lived Flex-R are actually much more than just the cost of replacement hardware. Not having to replace measurement systems means not having to shut down a reactor or to extend the downtime of a planned maintenance shut down. Avoiding downtime definitely boosts the bottom line.

Flex-R systems are designed so that all of the points can be verified post-installation. This means that you can verify the accuracy of your thermocouples at specific intervals – for example, during catalyst change-outs (typically around four years).

Keep in mind that thermocouples can typically begin to lose accuracy after 10 to 15 years. With a Flex-R multipoint solution, this is not a big deal. Given that you carefully monitor your points with a verification every four years, you can work proactively to extend the lifetime of a thermocouple or even swap out a less accurate one with an in-spec device at critical measuring points.

Other multipoint temperature measurement do not allow for thermocouples to be verified post-installation. At some point, you must either pull out the whole installation for verification or simply plan to replace the system every 10–15 years. Either way, you are looking at significant downtime that could be avoided by using a system with greater flexibility and a longer lifespan.

More accurate temperature measurement leads to improved process efficiency and a higher product yield. The Flex-R radial multipoint solution provides accurate readings for decades, and the distribution of the measuring points throughout the vessel means any problem areas that develop in the catalyst bed can be quickly identified and fixed.

With the Gayesco-Wika Flex-R multipoint system, you can count on decades of reliable, accurate temperature measurement. Moreover, the user-friendly design means you can verify the accuracy of your points during catalyst change-outs on a four-year cycle, “retune” as required, and then you’re set for another four years.

Let the experts at Gayesco-WIKA walk you through all the benefits and cost savings you can expect over the next 25 years when you choose the Flex-R solution for your pressure vessel measurement needs.

WIKA Sanitary Sensors Deliver Accurate Data in Food and Pharma Industries

Sanitary applications

Having access to accurate pressure and temperature readings at all times is essential in the 21st century food and pharmaceutical industries. Regulatory requirements demand 24/7 product monitoring as well as extensive documentation of the quality control processes.

Accomplishing this task means having accurate, reliable temperature and pressure measurement instruments in your production facilities, and setting up network infrastructure to support, distribute, and retain the data.

WIKA offers a complete line of accurate and reliable sanitary sensors, including a variety of pressure transmitters for applications in the food and pharma industries and a range of electrical temperature transmitters.

WIKA Sanitary Pressure Sensors

WIKA model IPT-10

WIKA Models IPT-10 and IPT-11

WIKA model IPT-10 and IPT-11 pressure transmitters are designed for use in the pharmaceutical, food, and beverage sectors. Available with a standard hygienic fitting or a flush diaphragm, these sanitary pressure sensors can be ordered with metallic or ceramic measuring cells in seven different housing variants. The transmitters are configured with a Device Type Manager (DTM) as a Field Device Tool (FDT).


WIKA Models UPT-20 and UPT-21

WIKA model UPT-20 and UPT-21 pressure transmitters are commonly used in the pharmaceutical, cosmetics, beverage, and food industries. Designed to meet hygienic standards, these transmitters have an applicable industry standard sanitary diaphragm seal. The pressure sensors feature a large, rotatable multi-functional display, and easy, intuitive menu navigation.

WIKA Model SA-11

SA_11WIKA SA-11 pressure transmitters are certified to meet all 3A and EHEDG sanitary standards for pressure and level measurement in the food, pharmaceutical, biotechnology, and cosmetic industries. These devices are designed for temperatures up to 150°C (300°F) and contain 1.5″ and 2″ Tri-Clamp® process connections, while offering 0.25% accuracy. This pressure transmitter is temperature compensated after the sanitary seal and system fill fluid have been installed, which provides a more stable output signal when exposed to changes in process and/or ambient temperature. This applied technology allows a full-scale measuring span down to 100 inches of water column.

S_10_3AWIKA Model S-10-3A

The model S-10-3A sanitary pressure transmitter is designed for use in the food, beverage, pharmaceutical, and cosmetics sectors. It is 3A compliant and available with a 3/4″, 1.5″ or 2.0″ Tri-Clamp® process connection. An integral cooling element can also be added for high or low temperature applications.

WIKA Model DPT-10

DPT_10WIKA’s DPT-10 differential pressure is a measurement device used within the pharmaceutical, biotechnology, food, and beverage industries. This highly accurate device features scalable measuring ranges, seven different housing variants, and meets or exceeds a variety of standards for use in hazardous areas. These differential pressure transmitters are configurable using a Device Type Manager (DTM) as a Field Device Tool (FDT).

WIKA Model F-20-3A

F_20_3AThe model F-20-3A NEMA 4X pressure transmitter was designed to meet the rigorous standards of the sanitary industry. It is a popular choice in the food, beverage, pharmaceutical, cosmetics, and biotechnology sectors. Only FDA-approved system fill fluid is used, and the transmitter can be ordered in standard pressure ranges from 15 psi up to 1500 psi. It is available with a ¾” and larger Tri-Clamp® connection and additional industry standard connections.

WIKA Electrical Temperature Sensors

TR22_AWIKA Model TR22-x Temperature Transmitter

The WIKA model series TR22-x RTD temperature transmitters are specifically designed for sanitary applications, and is popular in the food, beverage, biotechnology, and pharmaceutical industries. This RTD temperature transmitter features simplified calibration featuring a removable measuring insert. Materials and surface finish quality can be ordered to meet various standards, and a hygienic stainless steel head is easily cleanable in all mounting positions.

TR25WIKA Model TR25 In-Line Temperature Transmitter

The model TR25 in-line RTD temperature transmitter is one of WIKA most popular RTD temperature sensors. The hygienic design of the TR25 completely eliminates dangerous deadspaces and allows for rapid cleaning of the measuring points (supports SIP and CIP cleaning) and materials. Surface finish qualities can be ordered to meet almost all pharmaceutical industry standards.

TR53WIKA Model T53 Fieldbus Temperature Transmitter

WIKA model T53.10 fieldbus temperature transmitter, with FOUNDATION™ and PROFIBUS® PA fieldbus communication, can be used for temperature measurement with resistance thermometers (RTDs) or thermocouples. The transmitter can output differential, average, or redundancy temperature measurements. The small, explosion-proof model T53 temperature transmitter is compatible with all DIN form B connection heads.

Let WIKA help you navigate the regulatory maze of the sanitary industry. Our broad line of sanitary sensors are designed from the ground up to comply with applicable hygienic standards. Contact WIKA technical support to help you solve your problems or if you have any questions about pressure and temperature measurement in the sanitary sector.


Electropolished Stainless Steel Surfaces: A Must in Sanitary Applications

Sanitary process

It is vital to carefully design measuring instrumentation for sanitary applications in life sciences, biotechnology, cosmetics, pharmacology, and the food and beverage industry – particularly those devices that can come in contact with the process media. These instruments work under extreme hygienic conditions; at the same time, they must comply with numerous regulations. Ensuring impurities are not present within the manufacturing process requires repeated cleaning with harsh agents and sterilization.

Materials used in the construction of measuring instrumentation for sanitary applications must be biologically harmless, and should avoid corrosion that can contaminate process media or affect the instruments’ accuracy and repeatability. Austenitic 316L stainless steel meets these requirements and is a very good choice of material for sanitary applications. It is nontoxic and has good resistance to moisture, organic compounds, acids, and bases.

Also extremely important is the quality of the surface finish that comes in direct contact with process and cleaning agents. A smooth surface can be cleaned more thoroughly and easily than one with crevices and cracks. It can also prevent corrosion, the formation of deposits, and the possible onset and growth of bioburden.

What Is Electropolishing?

Grinding, sanding, blasting, and other mechanical methods are commonly used to smooth surfaces at the macro level. Electropolishing works at the micro level and produces an even smoother surface. It is the preferred method to treat stainless steel surfaces that will be in contact with process media. This electrochemical action reduces the roughness of the stainless steel surface and improves its quality by selectively removing microscopic high points, or “peaks,” at a faster rate of attack than the corresponding micro-depressions, or “valleys.”

The Benefits of Electropolished Surfaces

By removing the top layer, electropolishing produces a even smoother surface that is easy to clean and is free of irregularities that may promote corrosion, cracks, and deposits. Electropolishing also removes free iron from the stainless steel surface. After electropolishing, the surface is richer in nickel and chromium, and has a better passivation, or resistance to corrosion.

An electropolished surface will increase cleanliness down to a microscopic level. Instrumentation made with electropolished stainless steel is the choice for sanitary applications that involve any process media where hygienic conditions are of the utmost importance. By removing the peaks, the surface valleys are reduced and the finish is smoother. This minimizes the entrapment locations of process media during the cleaning process. This smoother surface finish also minimizes the locations where the cleaning agent can have residual holdup, which could contaminate the next process batch unless the residue is removed.

WIKA Instruments Use Electropolished 316L Stainless Steel

WIKA understands how surface quality can improve performance and reduce manufactures risk. We produce a wide variety of pressure, temperature, and level measuring instrumentation where all wetted parts are made of electropolished 316L stainless steel. Such instrumentation provides accurate data and can withstand the stringent requirements of sanitary applications without compromising the process.

WIKA’s TR21-B, a miniature resistance thermometer, and the M932.3A, a sanitary pressure gauge, are two products commonly used in sanitary applications for a variety of food and beverage, pharmaceutical, cosmetics, life sciences, and biotechnology processes. The electropolished stainless steel construction of the TR21-B and the M932.3A ensures high surface quality that enhances cleanliness and work well with CIP, SIP, and autoclave cycles.

WIKA closely follows the market and, as a result, designs and manufactures products that fulfill the needs of sanitary applications. Contact WIKA’s experts today to learn how measuring instrumentation, whose wetted parts have high-quality surfaces, can improve the performance of your application.

Getting to the Bottom of a RTD Sensor Reading Delay

The process engineers at a major chemical manufacturer were stumped. They were regularly getting very poor response times from their process temperature sensors and simply could not figure out why. The response times to temperature changes were consistently close to 30 minutes longer than they should have been, but all of the system diagnostic tests showed there was no problem with the sensing instruments.

After checking everything they could think of, the engineers contacted the provider of the temperature sensors and explained the problem. However, technical staff of that well-known instrument maker could not explain the unusual lag in their resistance temperature detector-type sensors.

Keep in mind that temperature control is essential in almost all chemical processes, and a half-hour lag is a major issue. Inaccurate temperature control can lead to expensive problems, such as spoiled batches, or, in a worst-case scenario, even lead to fugitive emissions or process leaks through damaged seals in valves, instruments, and equipment.

Poor Contact to Blame for Lagging Temperature Readings

In search of a solution, the lead Control System Engineer at the plant consulted with a temperature specialist from WIKA Instrument.

Within just a few minutes of conversation, WIKA’s temperature specialist was pretty sure he had a good idea what the problem was. He had heard of this lag problem before: It was almost always related to the sensor tip not actually making contact with the media to be measured. It is generally necessary to have direct contact between the sensor tip and the process media pipe or storage tank wall in order to get a near-immediate temperature reading. Any kind of a gap between the tip and the surface to be measured will result in a lag before the heat is transferred to the sensor.

After a plant walkthrough, the temperature specialist’s initial suspicion was confirmed. The temperature sensors weren’t long enough to touch the bottom surface of the process wells. This was causing the reading delay.

RTDs with Spring-load Assembly Resolve Delays

WIKA Model TR-10 Industrial RTD Assembly

WIKA Model TR-10 Industrial RTD Assembly

WIKA’s temperature engineering team suggested that a spring-loaded RTD (resistance temperature detector) assembly was the best way to make sure the sensor tip reached the inside bottom of extra-deep thermowells. WIKA provided the maintenance team at the plant with three sample spring-loaded sensor assemblies, which passed all tests and interfaced seamlessly with the plant’s distributed control sensors (DCS).

The new temperature sensors have performed flawlessly, plant management is happy and WIKA has another satisfied customer who has already expressed an interest in future temperature sensor business.

316L Stainless Steel: A Good Choice for Avoiding Corrosion in Sanitary Applications

Sanitary applications

Sanitary applications in pharma, life sciences, biotechnology, cosmetics, and the food and beverage industry are highly regulated and have very strict requirements. The equipment and instrumentation used in any sanitary application must be made of materials that are not toxic. Also, to ensure purity, equipment and instrumentation must be repeatedly and thoroughly cleaned and/or sterilized, and must avoid corrosion and any other source of contamination.

What Causes Corrosion?

Corrosion can be produced by the process media itself. It is more often caused by the products used for cleaning and sterilization, even though reliable and effective cleaning is vital in sanitary applications. Common clean-in-place (CIP) systems use highly corrosive alkali and acid-based solutions. Steam/sterilize-in-place (SIP) processes expose wetted parts to high-temperature and/or high-pressure cycles, and autoclaving can expose the measuring instruments’ internal components to moisture.

Corrosion affects the quality of your product: Corroded parts lead to leaks and will contaminate your media. In addition, corrosion in measuring instrumentation affects accuracy and repeatability. The losses associated with the need to discard contaminated batches and to stop the process to replace damaged instrumentation can be considerable.

What Is Austenitic 316L Stainless Steel?

Austenitic 316L stainless steel is highly recommended for the vast majority of sanitary applications. A low-carbon stainless steel, Austenitic 316L is inert to the majority of media found in sanitary applications and is highly resistant to acids. It has good resistance to the attack of organic products and withstands the attack of bases, including sodium hydroxide solutions – a common cleaning agent in CIP processes. In some cases, however, stronger nickel-based alloys such as Hastelloy® are necessary.

Certain materials – such as brass and brass alloys used by some other manufacturers of measuring instrumentation – are not the best choices for sanitary applications. These materials are appropriate for many other applications, but have very low resistance to corrosion. They also deteriorate easily in the presence of moisture, organic compounds, acids, and bases. Brass parts may compromise the integrity of the final product.

Why Choose WIKA Instrumentation?

Measuring instrumentation for sanitary applications must work under tough conditions while providing accurate measurements and repeatability. This instrumentation must be carefully and properly designed to perform well. The selection of the material used for the wetted parts and potentially exposed non-wetted components of sanitary gauges is critical. These parts are in direct contact with process and/or cleaning media, which may cause corrosion. WIKA uses Austenitic 316L stainless steel as the standard material for all the wetted and non-wetted metallic components of its gauges.


M93x.3A Sanitary Gauge

WIKA offers a complete line of mechanical and electronic pressure gauges, pressure transmitters, switches, and diaphragm seals that withstand the demanding requirements of sanitary applications. The sanitary pressure gauge, model type M93x.3A, for example, is ideal for measuring pressure in food and beverage, biotechnology, and pharmaceutical processes. The all-welded construction of this assembly complies with 3-A Sanitary Standards. All wetted parts are made of electro-polished 316L stainless steel and will not corrode, even after repeated CIP and SIP cycles. The internal metallic components are also constructed from 316L stainless steel to assist in avoiding corrosion due to cleaning methods. Model type M93x.3A works well for a wide range of pressures and resists high temperatures.

WIKA’s all-stainless steel gauges can endure harsh environments. They will not compromise your process and will provide repeatable, accurate data. Contact WIKA’s experts today to get more information about how WIKA’s stainless steel, corrosion-resistant gauges can benefit your sanitary application.

Magnetostrictive Float Technology is Superior to Guided-Wave Radar for Level Measurement of Foamy Liquids

Magnetostrictive sensor

Accurate level measurement is critical in industries ranging from pharmaceutical, food, and beverage to petrochemical manufacturing. Continuous manufacturing (24/7) depends on careful monitoring of the level of feed materials and process media in tanks, pipes, and other vessels throughout a facility.

Not all process media are the same, however, and accurate level measurement of various types of liquids requires different methods. More than a dozen technologies for measuring the level of liquids are known, but float technologies (including magnetic level indicators and magnetostrictive level sensors), ultrasonic, and radar-based methods are the ones most commonly used in industrial applications today.

Measuring liquid level within two-phase media – liquids that produce foam when agitated during a production process or generated within the process itself –is problematic for ultrasonic and guided-wave radar methods. These methods suffer from problems relating to beam divergence, and they have difficulty accurately measuring the interface where the foam ends and the liquid begins.

Magnetostrictive float technologies, on the other hand, operate by reference to a float on a stem, and produce reliable, accurate readings of liquid levels, even with foamy or frothy media.

Measuring Foamy Two-Phase Processes

Float level measurement technologies require knowing the specific gravity of the process media being measured. Using the specific gravity, the measuring instrument float can be properly specified for the liquid in the specific application. Foam or froth is not a problem, as the float will sink through the foam but remain buoyant on the liquid.

Level sensors based on a magnetostrictive, high-resolution measuring principle are used for level measurement of liquids by determining the position of a magnetic float.

The measuring operation begins with a current impulse, which generates an axial magnetic field along a magnetostrictive wire. The float is fitted with permanent magnets. When the pulse reaches the float, the two magnetic fields interact and a torsional stress is induced in the wire. By measuring the elapsed transit time between sending out the current impulse and receiving the torsional wave, it is possible to calculate the float position with a high degree of accuracy.

Note that some of the latest guided-wave radar systems are getting better at measuring liquid levels through many types of foams, but they tend to be more expensive and have more constraints (related to the shape of the vessel) than magnetostrictive float level measurement systems.

Don’t let a little foam interfere with the accuracy of your process instrumentation. With a reliable magnetostrictive level sensor from WIKA, you will get consistent, accurate level measurement – regardless of the size of an interface in a two-phase system.

Let the experts at WIKA help you figure out the best level measurement solution for your specific application.

Count on WIKA’s Dry Cell Sanitary Gauge for Accurate Pressure Readings

Flush diaphragm pressure gauge

Compliance and Risk, Operations, and Quality Control executives, along with process and maintenance supervisors in the pharmaceutical, biotechnology, and food and beverage industries, have been clamoring for highly robust, reduced-risk, accurate, easy-to-clean dry-cell pressure measurement technology for some time, and WIKA has delivered again.

The new WIKA Model PG43SA-S pressure gauge has been specifically designed for the demands of sanitary applications. This accurate and reliable sanitary gauge measures pressure using a revolutionary dry-cell technology, so there is no transmission fluid behind the diaphragm of any kind that could possibly contaminate the process media if a breach in the diaphragm was to occur.

Moreover, this new stand-alone gauge for sanitary applications utilizes a mechanical driven pressure measuring system in place of a hydraulic pressure transferring system, and the innovative design also offers high overpressure protection.

Fully Compliant with Sanitary Industry Standards

The PG43SA-S pressure gauge is compliant with all pharma and food industry standards, including 3-A and EHEDG Sanitary Standards. Because the pressure measurement design is based on a dry measuring cell, if a diaphragm were to breach, no liquid would enter the process media or piping system that would result in a contaminated process. Last but not least, this new sanitary gauge offers a flush-welded diaphragm element with hygienic process connections (clamp, threaded, VARIVENT, or BioControl), assisting with the minimization of dead-space within the process system.

Applications for the WIKA PG43SA-S Sanitary Gauge

When hygienic pressure measurement is required for applications in the pharmaceutical, biotechnology, food processing, and beverage industries, the new WIKA Model PG43SA-S pressure gauge is the ideal instrument for the job.

This reliable, robust sanitary gauge offers accurate mechanical pressure display for piping systems, fermenters, bioreactors, and other process vessels in manufacturing facilities and labs.

Specific applications include pressure or vacuum monitoring during manufacturing processes, cleaning operations, transportation vessels, or pressure testing. This multipurpose sanitary gauge can be used to measure almost any kind of liquid, paste, powder, or crystallizing media, and gases, compressed air, and vapors.

This dry-cell flush diaphragm pressure gauge is ideal for monitoring ultrapure steam generation and water (e.g., WIF, water for injection), and can also be used as a standalone pressure reading for tanks not requiring an external power supply. This gauge is an excellent choice for rough process conditions, vibrations, or pulsations.

Additional Features

The WIKA product development team came up with an innovative hygienic pressure gauge design that can handle both cleaning-in-place (CIP) and sterilization-in-place (SIP) operations, and can also be used in wash-down areas. Ease of cleaning leads to notable time and labor savings compared to traditional gauge designs.

The sensing diaphragm is constructed from Inconel Alloy 718 (high nickel content and approx. equal chromium content to 316L stainless steel) for high corrosion resistance. It is 2–5 times thicker than the typical 316L stainless steel diaphragm, making it less prone to physical damage.

The Model PG43SA-S pressure gauge features a polished stainless steel case and a rugged stainless steel movement to avoid potential corrosion of non-compatible materials with the cleaning agents. It is designed to operate in ambient temperatures from –20 to +60°C, and with media ranging from –20 to +150°C. This precision instrument has an accuracy class of ±1.6% of full scale.

As an additional convenience, the pressure instrument zero setting can be easily adjusted by removing the sealing plug on the top of the case, and with a slotted screwdriver reposition the gauge pointer.

Check out the product data sheet to learn more about WIKA’s newest dry-cell pressure gauge for the sanitary sector. As always, remember WIKA’s expert technical support team can answer any questions you have about sanitary gauges or other products.

Explosion-Proof, Low-Power WIKA E-10 Eco Pressure Transmitter Ideal for Wireless Monitoring in the O&G Industry


The ever-increasing need for more and better data has led to rapid growth in wireless monitoring. Big data is king today. And since modern control systems and decision-making are driven by data, it’s not surprising that the oil and gas industry is investing heavily in wireless monitoring systems for remote installations.

Wireless monitoring in remote areas comes with its own challenges, however. Most notably is the limited power supply. Conserving power is essential to ensure the pressure reading gets to the controller or monitor and that’s where low-power pressure transmitters can help.

Low-Power Pressure Transmitters for Wireless Monitoring

The new WIKA E-10 Eco explosion-proof pressure transmitter is sealed to withstand long-term exposure to the elements, and is available in a low-power 1–5 V configuration (6–30 VDC) that is ideal for wireless monitoring of drilling platforms, wellheads, pipelines, tanks, hydraulic systems, and gas compressors.

The E-10 Eco can run on battery or a solar cell power supply. Even with near-continuous monitoring, given a startup/settling time of ≤2ms, the transmitter can be expected to run for several years on a single battery.

Safety Comes First With the Explosion-Proof Transmitter

Safety is the utmost priority in the oil and gas industry, and the WIKA E-10 Eco pressure transmitter is approved as explosion-proof for Class I, II, III Div. 1 hazardous areas based on FM and CSA standards. This transmitter is completely sealed, so it can be used in areas where flammable gases might be generated.

Pressure Transmitter Designed to Withstand Stress

The E-10 Eco transmitter reliably provides pressure readings at an accuracy of 0.5% of span, and can take just about anything.

For example, this device features an extremely high resistance to vibration, pressure spikes, and moisture ingress (meets IP 67—NEMA 4x—ingress protection standards). It can also handle the harshest field conditions, making E-10 Eco an ideal transmitter for many applications in the O&G industry and related upstream sectors.

Specs and Features of the WIKA E-10 Eco

While extreme accuracy in instrument readings is required for some applications in the oil and gas industry, a reasonably accurate pressure gauge or transmitter is adequate for most. That’s where the WIKA E-10 Eco is ideal. This device was specifically developed for tasks such as wireless monitoring, where reliability and low-power draw are more critical than near-absolute accuracy. Note that this kind of application-specific design means the E-10 Eco costs notably less than other general-purpose explosion-proof transmitters.

You can order the E-10 Eco with output analog signals from 4 to 20 mA, or in a low-power version with DC 1–5 V.

Users can count on accuracy 0.5% of span under the standard temperature, atmospheric pressure, and humidity reference conditions (including non-linearity, hysteresis, zero offset, and end value deviation—measured error per IEC 61298-2).

The E-10 Eco also offers a non-linearity (per IEC 61298-2) of ≤0.2% of span (BFSL) and a non-repeatability of ≤0.1% of span.

The temperature error in the range 0 … 80°C (32 … 176°F) is: Mean temperature coefficient of zero point: ≤0.2% of span/10 K; mean temperature coefficient of span: ≤0.2% of span/10 K.

The WIKA E-10 Eco can run on battery or a solar cell power supply. Even with near-continuous monitoring, given a startup/settling time of ≤2ms, the transmitter can be expected to run for several years on a single battery.

Whether it’s on a drilling platform in the Gulf of Mexico or on a pipeline along the Alaska North Slope, you can count on the tough, explosion-proof WIKA E-10 or E-10 Eco to get you the pressure data you need – 24 hours a day, seven days a week. Our knowledgeable technical staff are happy to answer any questions you have about the latest addition to WIKA’s industry-leading line of pressure transmitters.

No-Hassle Liquid Level Measurement with WIKA Sanitary Optical Level Switches

Optoelectric level switch

Accurate liquid level measurement is critical in the food and beverage, pharmaceutical, and biotechnology industries. Various technologies have been developed for measuring liquid levels in a range of sanitary applications, including float, reed chain, magnetorestrictive, and optoelectronic methods. All of these methods, however, have notable differences in terms of accuracy, size, and ease of calibration and cleaning.

Optical level switches are one of the newest methods for monitoring liquid levels in the sanitary industry.

The WIKA Model OLS-F1 Optical Level Switch is specifically designed for the sanitary industry, and it offers a number of advantages over traditional level switches, especially in terms of its compact design and autoclavability.

Operation of Optical Level Switches

Optical level switches sense the level of the liquid in a vessel using light. These devices operate using an optoelectronic sensor that monitors the liquid level in a pipe, tank, or other vessel. The sensor itself is an infrared LED emitter and a photo-transistor receptor assembled as a single unit.

The light from the LED is focused within the prism at the tip of the sensor. While the sensor tip remains above the liquid, the light is reflected within the prism to the receptor. However, when the liquid level reaches and covers the tip, the light beam is interrupted, and the light no longer — or only weakly — reaches the receptor. The light receptor reacts instantly to this change and initiates a switching operation within milliseconds.

Enjoy Easy, Low-maintenance Level Measurement with the WIKA OLS-F1 Optical Level Switch

The WIKA Model OLS-F1 Optical Level Switch has been designed to solve several long-standing issues in the sanitary industry. This very small level measurement unit will fit in almost any process pipe or tank, process connection down to a 3/4” tri-clamp. The electro-polished surface finish substantially reduces product contamination and adhesion due to the microscopic smoothness and shortened cleaning cycle time. This user-friendly level switch is accurate to +/- 0.5 mm, and can be mounted vertically or horizontally. This level switch can be supplied with various sanitary process connections: tri-clamp per ASME BPE, DIN 32676, clamp per ISO 2852, and other industry standards.

Sanitary industry executives and process engineers have been lobbying for autoclavable instrumentation for years, and WIKA continues to deliver with new products designed to meet industry needs. With the OLS-F1, autoclaving operations can be safely conducted up to a temperature of 134°C.

Why take chances by using level measurement devices that were not specifically designed for the stringent requirements of the sanitary industry? With the WIKA Model OLS-F1 level switch, you can be certain you are using the right instrument for the job. These robust, accurate switching devices can be assembled to virtually any process vessel, will minimize contamination, and can be cleaned quickly and easily.

WIKA’s team of highly trained technical support staff are more than happy to answer any questions you have about optical level switches or about our line of award-winning line of sanitary industry products.

WIKA Wins Lawsuit: Court Finds Ashcroft Made False Claims about Safety, Flammability of Its 1279 Gauge


Technical specifications for measurement instruments play an integral role in operating and purchasing decisions, helping you determine whether a pressure, temperature, level or flow solution will function accurately and safely in an application. In data sheets and other product documentation, instrument manufacturers typically detail the materials of construction, safe operating parameters and other critical information. Misinformation about such specifications can contribute to misapplication, which can potentially jeopardize the reliability and safety of operations.

In the WIKA v. Ashcroft lawsuit, a jury and court found that Ashcroft, Inc. intentionally published false information concerning the flammability and safety of its 1279 Duragauge® product and made false claims regarding WIKA’s XSEL® process gauge. Specifically, Ashcroft mispresented the 1279 gauge case materials and its risk of spreading fire. This misinformation appeared in Ashcroft’s 1279 data sheet and a product information page.

Pocan® Thermoplastic vs. Plenco® Phenolic

In WIKA v. Ashcroft, the jury and court found that Ashcroft falsely stated in its data sheet that the entire case material of Ashcroft’s 1279 Duragauge is made of a phenolic material, Plenco 02370, when the front ring and back cover of the gauge case are actually made of polypropylene.1 Based on Ashcroft’s testing and third-party testing introduced at trial, the type of polypropylene material Ashcroft uses for the back cover and front ring of the 1279 Duragauge® case burns, does not self-extinguish, and poses the risk of spreading fire when exposed to an open flame.

Moreover, Ashcroft misrepresented the properties of the XSEL process gauge in its product information page. The court ruled that Ashcroft’s own open-flame testing actually showed that the XSEL gauge case, made from the specific thermoplastic Pocan B4225, immediately self-extinguished after exposure to the flame. However, Ashcroft publicized the opposite.

Screen Shot 2017-03-17 at 1.53.15 PM

Screenshot of the open flame test video

At trial, a third-party flammability expert, Barry E. Newton, PhD, P.E. (Registered Professional Engineer) with WHA International, testified that that the XSEL gauge is safer in a fire than the Ashcroft gauge. Dr. Newton is a former NASA scientist and a recognized expert in fire sciences, material science, and flammability of materials. A side-by-side comparison of Dr. Newton’s testing can be seen in this video.

Aside from low flammability, Pocan thermoplastic is the preferred material for gauge cases because it offers high-impact resistance, excellent form stability, low water absorption, limited susceptibility to stress cracking, good chemical resistance, and above-average electrical insulating properties.

The court-ordered corrective advertising regarding the false claims is on Ashcroft’s website:

The case recently settled after Ashcroft’s post-trial motions to reverse or vacate the judgment were denied by the court.

To read more about the WIKA v. Ashcroft lawsuit and to review court documents and other resources, visit Also, WIKA’s knowledgeable technical staff is available to answer any questions you have about the XSEL process gauge, and your pressure, temperature, level, and flow measurement requirements.

Polypropylene is used for the back cover of the dry case version of the 1279, other versions use a different non-phenolic material for the back cover, and all versions have a polypropylene front ring. UPDATE – May 16, 2017:  According to Ashcroft’s 1279 Data Sheet revised sometime in May 2017, Ashcroft has apparently changed from the flammable polypropylene so that all versions of its 1279 gauges use polycarbonate for the front ring and back cover.  (See 1279 Data Sheet, Rev. A 05/17).  WIKA has not independently confirmed this product change, or when such versions of the 1279 became available to the market.  Any 1279 gauges purchased before this change became effective still present the flammability concerns addressed above and in the lawsuit because they contain polypropylene back covers and/or front rings.  According to Ashcroft, the entire case (body, front ring and back cover) of Ashcroft’s 1259 gauges are made from polypropylene.  (Ashcroft 1259 Data Sheet “06/16”, available on Ashcroft’s website as of May 16, 2017).

WIKA Has a Solution for Tight Spaces When Replacing Glass Gauges

WMI series

Consistent and reliable, magnetic level indicators are widely used in many sectors, including the petrochemical industry. The operation of these cost-effective instruments is simple and elegant: A float resides within a chamber that, most commonly, is attached to the side of a tank or vessel via piping. Inside the float is a magnet assembly. A magnetically affected visual indicator is attached to the outside of the float chamber. As the liquid level within the tank – and thus the chamber – increases or decreases, the float rises or falls with it. Magnetic wafers or flags on the indicator react with the magnet assembly within the float, giving users an accurate reading of the liquid level. Because the process liquid is completely sealed in the chamber of this instrument, the dangers and maintenance headaches associated with glass reflex or transparent gauges is eliminated.

A glass gauge fits into a specific application with the use of various pipes, nipples, fittings, and so on. The piping allows the process to connect to the gauge from the back or from the top and bottom of the gauge. Magnetic level indicators, however, often are not exact replacements for glass gauges due to their floats – the heart of the instrument. The float must be designed for the process condition to take into account the individual application’s pressure, temperature, and specific gravity. In order to be buoyant in virtually any liquid, it must contain a corresponding amount of volume. In short, for the float to work properly, its size varies depending on the liquid. Sometimes a float is 6 inches long, but in rare instances it can be more than 30 inches long! The magnet inside the float is usually located about 2 inches from the top of the float. This leaves the balance of the length of the float, creating wasted space. The pipe chamber obviously must contain the entire float, so it has to be designed and manufactured to accommodate this additional length.

Like glass gauges, magnetic level indicators can be attached to a process vessel with a variety of connection options. Most common for both types of visual indicators is from the side, but in some instances these instruments are connected from the top and bottom of the chamber, with no side connections at all. This is where we run into problems when replacing glass gauges. Existing piping may have been designed precisely for the size of a glass gauge. Although a magnetic level indicator is a desirable replacement, the additional space needed to encompass the float makes some retrofits impossible. It’s little wonder that when customers are ready to update their technology, some fear the plumbing headache that may come with magnetic level indicators.

Real-life problem – real-life solution

Engineers at a major petrochemical company faced this problem when trying to replace a faulty glass reflex gauge with a safer and more reliable magnetic level indicator. With this replacement, they could also improve the visibility of the level of liquid propane and butane in their vapor knockout pots. The existing piping to the glass gauge allowed for connections directly on the top and bottom of this instrument. However, because of the additional length of the magnetic level indicator caused by the float length, it didn’t appear possible that this would be a successful retrofit. The customer didn’t want a major plumbing project. Unable to resolve the dilemma, the company’s engineers called in WIKA and its team of experts, who were able to tap years of past experience to come up with an answer.

modified level gauge

Front view (left) and side view (right) of the modified magnetic level indicator customized for a vessel with minimal available space.

Since the entire magnetic level indicator would not fit between the customer’s existing flange connections, WIKA had to get creative. By taking the normally positioned side branch connections from the magnetic level indicator chamber and adding two 90° elbows, WIKA’s experts were able to fit a longer instrument into the shorter existing piping configuration without additional work from their piping staff: The addition of the elbows made it possible to utilize existing connections and to easily install the upgraded instrument. In doing so, the connection locations allowed for a duplication of the liquid level in the magnetic level indicator chamber to the knockout pot. With this modification, the customer was able to have accurate, reliable, and safer level indication that now starts and ends where the side connections are bolted. The engineers were so pleased with the custom solution that they ordered four units.

WIKA is here to help

WIKA offers a full line of magnetic level indicators. The devices in the WMI series are robust and dependable, providing accurate level indication for many years with little or no maintenance. The WMI’s floats are built specifically for each application to supply greater accuracy. Magnet assemblies are carefully selected to minimize float and chamber size and length. Chambers are made of nonmagnetic materials such as stainless steel, Hastelloy, Inconel, and Monel, and adhere to the client’s specifications to fit perfectly within existing or new processes. The visual indicator is easy to read and comes with a ruler marked in feet/inches, meters/centimeters, or percentage, or it can be tailored to individual requirements. WMIs can be fitted with a variety of different process connections, plus vent and drain options. Other add-ons include high temperature and cryogenic insulation, steam tracing and electrical heat tracing, reinforced flange supports, and liquid gas construction.

WIKA’s experts can modify and adapt components to fit your particular needs and improve your processes. They will work with you and find a solution to your measuring issues. Give them a call today.