- Protection against corrosive media: Diaphragm seals isolate the gauge from corrosive liquids and gases, preventing damage to the indicator and ensuring accurate readings.
- High-temperature resistance: Diaphragm seals use materials that can withstand high temperatures, such as PTFE and Monel, allowing the application of the gauge in high-temperature applications without affecting accuracy.
- Vibration resistance: In high-vibration applications, diaphragm seals reduce the vibration transfer to the gauge, reducing the risk of damage and ensuring accuracy.
- Media compatibility: The diaphragm material can be selected based on compatibility with the process media, ensuring accurate readings and preventing damage to the gauge.
- Longer service life: A diaphragm seal with a pressure gauge in corrosive, high-temperature, and high-vibration applications can extend the service life of the pressure gauge, reducing the need for maintenance and replacements.
Providing problem solving and educational information for topics related to industrial steam, hot water systems, industrial valves, valve automation, HVAC, and process automation. Have a question? Give us a call at (800) 892-2769 | www.meadobrien.com
The Role of Industrial Diaphragm Seals
The Ashcroft Acid Leak Detection Assembly
While dangerous acids have been safely used in industrial applications for many years, specifying proper pressure instrumentation for these locations requires unique expertise. Ashcroft understands the dangers of acid leaks. That is why they developed the Acid Leak Detection (ALD) assembly.
ALD is a special yellow coating that changes to red once it is exposed to acids with a pH of ≤ 3.0, providing visual indication of a leak of process media.
For more information about the Ashcroft Acid Leak Detection system, contact Mead O'Brien. Call them at (800) 892-2769 or visit their website at https://meadobrien.com.
The Ashcroft E2 Sanitary Pressure Transmitter
Ashcroft E2 Sanitary Pressure Transmitter
Key Features:- Available with 1.5" and 2.0" Tri-Clamp® connection
- 3A approved
- Wide selection of electrical terminations
- Customized configurations
- External magnetic offset and span adjustment
- Accuracy: ±0.25%, ±0.5% or ±1.00% of span
- Process Connection: 316L stainless steel
- Pressure Range: vacuum to 1,000 psi
- Ingress Rating: IP66, IP67 or IP69K (consult factory)
- Surface Finish: 12 to 20 Ra electropolished diaphragm
Understanding Differential Pressure Measurement: Differential Pressure Gauge Example
This video (courtesy of Ashcroft) does an outstanding job illustrating the concepts of differential pressure and flow measurement using the differential pressure method.
Engineered restriction devices are often inserted into a closed pipe system to create a differential pressure for the purposes of measuring fluid flow rate. These restrictions can come in the form of an orifice plates, Venturi, wedge, and other designs.
To measure the differential pressure, taps must be installed on both sides of the plate. The upstream side will always produce the greater pressure, and is referred to as the high side. Conversely, the downstream pressure will always be the lesser value, due to the obstruction.
A differential pressure gauge's range is based on the maximum difference that can be expected as a result of the restriction. The gauge's dial will display the differential pressure in units of pressure measurement, like psi or bar. By applying the linear square root relationship between flow rate and pressure, the gauge style can be scaled in a specified rate of flow, such as gallons per minute. A dual scale dial can also be created to display both the flow rate and the differential pressure.
Another important consideration is the maximum line pressure, also referred to as the static pressure. The higher the static pressure, the more robust the gauge must be to contain it. That's why it's crucial to ensure that the gauge carries a static pressure rating that exceeds the highest pressure in the line.
For more information about differential pressure gauges, transmitters, and flow measurement, contact Mead O'Brien at (800) 892-2769 or visit their web site at https://meadobrien.com.
Calibration Procedures for the Ashcroft P-Series Snap Action Switch Pressure Control
The Ashcroft P Series pressure control is a precision device which features a snap action switch. Fixed deadband is available with single or dual SPDT independently adjustable switches with various electrical ratings. Adjustable deadband is available with a SPDT switch with various electrical ratings. Several wetted material constructions for compatibility with pressure media may be obtained.
The “P” Series Ashcroft snap action pressure switch is available in explosion-proof NEMA 7 & 9 configurations. The enclosure is an epoxy coated aluminum casting.
This video describes how to calibrate the Ashcroft P-Series.
For more information about Ashcroft, Inc. products, contact:
Mead O'Brien
https://meadobrien.com
(800) 892-2769
NACE Standards - Measuring the Pressure of Sour Gas and Crude

Today, NACE offers over 150 standards that address metal corrosion in a vast number of applications ranging from exposed metal structures to corrosion resistant coatings on railroad cars.
The following NACE Measuring Pressure of Sour Gas and Crude White Paper (courtesy of Ashcroft) discusses NACE standards that specifically address corrosion resulting from expo- sure to sour gas or sour crude.
You can download the entire NACE Standards Sour Gas and Crude White Paper here, or review it in the embedded document below.
For more information, contact Mead O'Brien at (800) 892-2769 or visit their web site at https://meadobrien.com.
Industrial Thermowells: Sometimes Taken for Granted, but Critically Important
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Thermowells come in a wide variety of shapes, materials, and sizes. (Courtesy of Ashcroft) |
Thermowells are critically important for installations where the temperature element (RTD, thermocouple, etc.) must be replaceable without de-pressurizing the process.
Thermowells may be made out of any material that is thermally conductive, pressure-tight, and not chemically reactive with the process. Most thermowells are formed out of either metal (stainless steel or other alloy) or ceramic materials.
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Typical RTD thermowell installation. |
Five Important Criteria in Applying Pressure Gauges
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Process pressure gauge. (Ashcroft) |
While there are millions of possible combinations of shapes, sizes, options and materials, pressure gauges all share the five following application criteria, required for safe use and long product life.
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Diaphragm seal. (Ashcroft) |
2 - Process Media Temperature: Very hot media, such as steam or hot water, can elevate the gauge's internal temperature leading to failure or an unsafe condition. For high temperature applications, the use of a "pigtail siphon" or diaphragm seal is recommended. Siphons act as a heat sink and lower the exposure temperature. Diaphragm seals isolate the gauge from the higher temperatures.
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Pigtail siphon. |
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Snubber |
5 - Mounting: Pressure gauges are standardly available with bottom (radial) and back connections. NPT (National Pipe Thread Taper) threaded connections are generally the standard. Many other process connections are available though, such as straight threads, metric threads, and specialized fittings. Make sure you know how the gauge is being connected. When mounting, pressure gauges should be almost always be mounted upright.
For more information about pressure gauges, contact Mead O'Brien by visiting https://meadobrien.com or by calling (800) 892-2769.
Industrial Boiler and Burner Limit Control Switches
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Ashcroft Limit Control Switch |
Ashcroft Materials Compatibility and Corrosion Guide
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Ashcroft products. |
The reference is intended to serve solely as a general guide in the recommendation of materials for corrosive services and must be regarded as indicative only and not as any guarantee for a specific service. There are many conditions which cannot be covered by a simple tabulation such as this, which is based on uncontaminated chemicals, not mixtures.
Many of the chemicals listed are dangerous or toxic. No material recommendation should be made when there is insufficient information, a high degree of risk, or an extremely dangerous chemical. The end user is responsible for testing materials in his own application, or for securing the services of a qualified engineer to recommend materials.
The end user is responsible for the choice of product(s) in his own application, based upon his own determination of the materials, chemical, and corrosion factors involved. THIS GUIDE AND ITS CONTENT ARE PROVIDED ON AN “AS IS" BASIS WITHOUT WARRANTY OF ANY KIND.
You can refer to the embedded document below, or you can download your Ashcroft Corrosion Guide PDF from this link.
What Are Isolation Rings?
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Isolation Rings (Ashcroft) |
The ring design includes ring has a flexible inner cylinder that prevents process media from collecting in the instrument, and therefore assuring reliable and continuous pressure measurement. An integrated needle valve allows for fast and easy removal for instrument repair, replacement, or calibration without interrupting the process media flow. The needle valve can also be used for pulsation dampening.
Watch the video below for a more in-depth understanding of how Isolation Rings are installed and operate.
For more information, contact Mead O'Brien by calling (800) 892-2769 or visiting https://meadobrien.com.
How to Use the Ashcroft 1305 Deadweight Tester
Industrial Pressure Switches
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Industrial Pressure Switch (Ashcroft) |
Normal status of a switch is the resting state with stimulation. A pressure switch will be in its “normal” status when it senses low or minimum pressure. For a pressure switch, “normal” status is any fluid pressure below the trip threshold of the switch.
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Pressure Switch Symbols |
Pressure switches using micro type electrical switches and force-balanced pressure sensors is another common design. The force provided by the pressure-sensing element against a mechanical spring is balanced until one overcomes the other. The tension on the spring may be adjusted to set the tripping point, thus providing an adjustable setpoint.
One of the criteria of any pressure switch is the deadband or (reset pressure differential). This setting determines the amount of pressure change required to re-set the switch to its normal state after it has tripped. The “differential” pressure of a pressure switch should not to be confused with differential pressure switch, which actually measures the difference in pressure between two separate pressure ports.
When selecting pressure switches you must consider the electrical requirements (volts, amps, AC or DC), the area classification (hazardous, non-hazardous, general purpose, water-tight), pressure sensing range, body materials that will be exposed to ambient contaminants, and wetted materials (parts that are exposed to the process media).
Dampening the Effects of Vibration on Industrial Pressure Gauges
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Vibration must be considered when applying pressure gauges. |
While a liquid filled gauge does solve the oscillation problem, it does have a drawback. The liquid in the gauge presents its own set of operational issues requiring consideration in any application.
Provision should be made to check and maintain the liquid level in the gauge
A liquid filled gauge is an additional source of potential leakage in a facility
Ashcroft, a globally recognized manufacturer of gauges for commercial, industrial, and laboratory use, offers a different solution that provides the deflection dampening of a liquid gauge without liquid fill. Available on many of their gauges, the "Plus" option enables stable gauge face display in a dry gauge.
The video below provides a side by side demonstration of a liquid filled and a Plus gauge, so you can see the performance of both types. Share your process gauge requirements and challenges with instrumentation experts, combining your process knowledge with their product application expertise to develop effective solutions.
Understanding Differential Pressure or Delta-P
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Differential pressure or Delta-P |
With the filter no longer functioning properly, the contaminants can escape into the process. This is why proper monitoring of pressure drop is crucial. So how can we measure the DP? Placing taps both before and after the filter, a differential pressure measuring instrument can be connected to detect the high side and close side pressures. the instrument will report the difference between the two sides. The saturation point will be indicated when the Delta-P value reaches a predetermined threshold. This value is derived from a calculation that factors in the flow rate, fluid viscosity, and filter characteristics.
When specifying a differential pressure instrument there are two important factors to consider. The first is the DP range, which is based upon the most difference in pressure that the restriction is likely to produce. The second is the instruments ability to contain the line or static pressure level.
For more information on pressure measurement, call Mead O-Brien at (800) 892-2769 or visit www.meadobrien.com.
Here is a great video, courtesy of Ashcroft, that provides an excellent visual understanding of differential pressure.
Types of Pressure Measurements Used in Process Control
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Pressure gauge (courtesy of Ashcroft) |
As with any type of measurement, results need to be expressed in a defined and clear way to allow everyone to interpret and apply those results correctly. Accurate measurements and good measurement practices are essential in industrial automation and process environments, as they have a direct effect on the success of the desired outcome.
When measuring pressure, there are multiple units of measurement that are commonly used. Most of these units of measurement can be used with the international system of units, such as kilo, Mega, etc.