When Should You Use Diaphragm Seals?

By: Instrument Guru, December 2, 2014
 
Pressure gauges are often used in extreme conditions in industrial processes, and some gauges are specifically designed for use in these difficult process environments. These tough process gauges typically include features such as hardened housings, liquid-filled casings, and a stress-reducing Bourdon tube design, and they are often equipped with a diaphragm seal to prevent contact between the hot or corrosive media and the gauge itself. A diaphragm seal protects pressure gauges from dangerously hot, viscous, or corrosive media and dramatically extends the lifetime of the instrument.
 

Understanding diaphragm seals

 
A diaphragm seal is connected to a gauge as either a direct connection or by way of a capillary. An elastomer or flexible metal diaphragm keeps the process media from contacting the workings of the gauge. The chamber between the diaphragm and the gauge is filled with a fluid that accurately transfers the pressure of the process media by hydraulic means. Any change in process media pressure is transmitted through the flexible diaphragm into the system fill fluid, which then connects to the Bourdon tube of the gauge.
 
Diaphragm seals can be easily mounted onto gauges using threaded, flanged, in line, sanitary, or other types of connections.
 
In most cases, diaphragm seal bodies and the diaphragms themselves are stainless steel, but instrument industry leaders like WIKA also produce diaphragm seals from other materials including carbon steel and Hastelloy® C-276 for specific applications. WIKA’s diaphragm seals are designed to operate in pressure applications from 10″ Hg to 20,000 psi and at media temperatures between -130°F and +752°F.
 
Diaphragm seals are also installed on pressure transmitters and switches exposed to extreme conditions.
 

When to use a diaphragm seal

 

• Protective diaphragm seals are typically used in applications where direct contact with the process media will degrade the instrument. Diaphragm seals should be considered under conditions including:
• High-temperature media – A diaphragm can be designed to include a cooling element; for example, a diaphragm seal with an 8″ cooling tower can tolerate temperatures up to 750°F.
• Corrosive media – WIKA can provide diaphragm seals made of a variety of custom alloys, including PTFE, gold and silver, or carbon steel. WIKA’s Metal Bonded Diaphragms are designed for processes requiring Hastelloy®, Monel® and Tantalum flush diaphragms.
• Viscous or crystallizing media – Using pressure seals reduces the number of connections in a process, minimizing internal cavities where clogs typically form.
• Media with suspended solids – Diaphragm seals minimize clogging in process applications such as pharmaceutical, pulp and paper, food and beverage, chemical, and waste water.
• When overpressure protection is required – WIKA has designed a diaphragm seal with a continuous-duty contoured diaphragm bed for robust overpressure protection.
• When sanitary cleanliness is required – WIKA’s patented InLine Seal™ makes sure that your process system does not develop “dead spaces” that encourage bacterial growth.
• Highly toxic or dangerous media – An all-welded process gauge and diaphragm seal system offers extra protection to minimize the chance of any toxic media escaping.

Top quality WIKA diaphragm seals specifically designed around your processes can dramatically extend the lifetime of your pressure measurement instrumentation and lead to significant cost savings. Contact us to learn more about how a small investment in the right diaphragm seals pays off over the long run.

Forberg Scientific, Inc.
P: 855-288-5330
E: mechanicalsales@forberg.com
www.forberg.com

Parker Autoclave 1-1/2" Fittings & Tubing - Up to 15,000 psi

High Flow and High Pressure don’t always mix…

If you’ve ever worked with high pressure fluids you know that with high pressure thick-walled tubing, the increased wall thickness takes away flow area (tubing maintains the O.D.).

So when flow is critical to your process as with Nitrogen Injection, it isn’t unusual to see dual (or even triple) tubing runs to meet pressure and flow requirements. Not any more…

Parker Autoclave Engineers continues our reputation of excellence as we design the hardware your application requires that will increase production while saving you money. We are happy to announce the availability of our NEW Medium Pressure 1½” Fittings and Tubing that are designed for working pressures up to 15,000 psi (1,034 bar).

With one run using this size tubing (flow area = 0.69 in2), you have nearly the same flow area as two 1” (combined area = 0.74 in2) tubing runs while maintaining the same system pressure with less opportunity to leak… at a lower cost to install.

For specifications and ordering information please consult out “Medium Pressure Fittings and Tubing” brochure in our catalog or online at www. Autoclave.com. As always, Parker Autoclave products are backed by our global sales and support network and friendly service is only a phone call away.

Parker Autoclave Engineers – High Pressure is our business.

If you would like to receive pricing & availability on Parker Autoclave fittings please contact Forberg Scientific, Inc.    P: 855-288-5330    E: mechanicalsales@forberg.com

Heat Trace Cable Approved for Branch Sprinkler Systems Nelson LT and CLT Cable

Appleton Group proudly announces that Nelson’s LT and CLT self-regulating heating cables now have CSA and CSA-US approval for use on mains and branch sprinkler systems in both the United States and Canada. In addition, these heating cables now meet  IEEE 515.1-2012, and CAN/CSA C22.2 No. 130-03 standards.  And when installed according to instructions will meet the requirements of the NEC 2014-NFPA 70, and CEC 2015

 

Nelson self-regulating electric heat trace cables are now listed and certified for freeze protection from the main water lines to the sprinkler heads. It’s a simpler, safer method of freeze protection.

• Simple - Far less maintenance and lower costs than existing methods.
• Reliable - Water will always be immediately available to the sprinkler heads rather than having to travel from the main lines. No potentially harmful antifreeze chemicals are needed.

What makes heat trace better?

• Provides automatic heat to branch sprinkler lines when needed. Self-monitoring temperature controls ensure that heat is applied to pipes as soon as it’s needed.
• Self-regulating heat output means the system automatically regulates temperature, reducing electricity use and allowing for cable to be overlapped without the risk of hot spots.

A better alternative - Up until now, you have only had two options for freeze protection from main water lines to sprinkler heads. Unfortunately, both these options come with downsides.

• Dry systems require paying a professional annually to flush out the sprinkler system. Dry systems also mean that it may take water longer to reach the sprinkler system from the main water lines in the event of a fire, and the empty sprinkler system is vulnerable to rust caused by trapped moisture.
• Chemical systems require adding antifreeze to the pipes. This method requires you to buy and add chemicals regularly. It also carries the risk of antifreeze leaking into drains and ground water, or being sprayed in your facility during a fire.

Applications:

• Warehouses
• Loading docks
• Outdoor areas for Restaurants, banquet halls and night clubs
• Arenas and stadiums
• Walk-in freezers
• Car washes
• Parking garages

   

With the addition of these new approvals, Nelson LT and CLT  heating cables will now be able to provide complete protection for fire sprinkler systems.  For more information, please visit our website at www.forberg.com or contact Forberg Scientific, Inc. Customer Support and Technical Support at 1-855-288-5330 for any additional  inquires.