Custom Values Eliminate Leaks

Nov. 21, 2007
Precision leak-testing instruments can detect pressure changes of 0.00001 psi and, from that, calculate leak rates.

The equipment relies on valves to channel flow and, for accuracy and repeatability, this internal hardware must itself be leakproof.

One major instrument manufacturer found that standard pneumatic valves are themselves too leaky, producing erratic test results. They turned to Humphrey Products, Kalamazoo, Mich., for a custom valve manifold with virtually zero leakage.

Company engineers started with a standard, poppet-type cartridge valve with 1/8-in. orifice, flow rating of 25 scfm ar 100 psig, and maximum pressure rating of 215 psig. They modified it to hold O-ring poppet securely under high pressure. A new stem effectively traps the Buna O-ring, keeping it from blowing out or distorting under high test pressure.

A Humphrey Mizer valve serves as the pilot operator. It consumes only 0.5 W of power, resulting in little heat dissipation, and that ensures the system will not affect instrumentation accuracy.

Valve manifolds were tested for 200,000 cycles and periodically checked for leaks. In each case, pressure drop was less then 0.002 psi over 30 sec at 100 psi - equivalent to 0.0025-scc/min flow - 1/20th of the leak rate permitted by the customer's specifications. The unit is now in full production.

O-ring seals in the valve poppet give extremely low leakage.

 

Sponsored Recommendations

NEW Low Profile, Ultra Compact Power Supplies

March 13, 2024
Learn more HERE about Altech's Power supplies!

Altech's Liquid Tight Strain Relifs Catalog

March 13, 2024
With experienced Product Engineers and Customer Service personnel, Altech provides solutions to your most pressing application challenges. All with one thought in mind - to ensure...

Industrial Straight-Through Cable Gland

March 13, 2024
Learn more about Altech's cable glands and all they have to offer for your needs!

All-In-One DC-UPS Power Solutions

March 13, 2024
Introducing the All-In-One DC-UPS, a versatile solution combining multiple functionalities in a single device. Serving as a power supply, battery charger, battery care module,...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!