what is an air stop?

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ENVACON has been in the business of designing and supplying engine air-intake shut-off valves since 1999. In addition to this experience, the company principles have an additional 25+ years of experience designing, manufacturing, and supplying engine shut-offs via prior employment with the original manufacturer of such devices. Our experience includes direct involvement in engine over-speed research and testing at multiple international diesel engine manufacturers. ENVACON is not just selling a low-cost valve; we offer a safety device specifically designed to address ALL the possible risks encountered during an 'inhaled combustible gas' induced diesel engine over-speed scenario. AIR STOP valves are truly 'positive' air intake shut-off valves.

By design, butterfly gates and the sealing surface(s) are directly in the airflow during engine operation and are prone to contaminant build-up and possible damage or wear resulting in reduced seal capability over time. 

The in-line butterfly gate and shaft result in a 15-20% bore reduction, restricting engine airflow and adversely influencing engine performance. 

Butterfly valves do not offer the long-term durability for on-engine heat and vibration applications. Engine airflow dynamics can cause the 'in-line' butterfly valve gate to continuously pulsate or vibrate, and combined with innate engine vibrations, the gate shaft bearing support is prone to wear over time. This results in non-concentric shaft support and potentially seized or non-functional gates, and critically, a reduced or inability to completely seal off the engine airflow when required. 

Butterfly valve closing times are typically measured in multiples of seconds versus a fraction of a second for specifically designed gate valves. In an 'inhaled combustible gas induced' diesel engine over-speed, seconds count and they can be the difference between scorched engine bearings requiring an overhaul, and more critically, catastrophic engine failure and/or ignition of the surrounding combustible gas cloud. 

Butterfly valves DO NOT address ALL the risks encountered during an ‘inhaled combustible gas induced’ diesel engine over-speed.

Gate valves offer a full and un-obstructed through-bore and fractional second gate closure, and when specifically designed for the application, as the AIR STOP valve has been,  they address ALL the risks encountered during an ‘inhaled combustible gas induced’ diesel engine over-speed.

The ENVACON AIR STOP valve design draws on experience gained from shut-off valve applications dating back to the late 1970’s {including direct ENVACON and prior employment shut-off design, manufacturing, and installation experience}. This includes direct involvement with international diesel engine manufacturers and their required design specifications and durability requirements, Military applications, and installation applications across the range of available diesel engine equipment makes and models for both stationary engine and mobile heavy equipment, and automotive and highway truck applications. 

ENVACON is an ISO Certified company

ENVACON implements and maintains Advanced Quality Product Planning and Control Plans (APQP) and Production Part Approval Process (PPAP) risk management verification programs and procedures.

Prior to shipment, every valve that we manufacture undergoes complete testing, including but not limited to; pressure vessel integrity, gate seal ability, valve cycling, confirmation of actuation functionality and specifications, and gate position indicator switch testing (if installed). The test results are recorded and filed against the valves unique serial number. The serial number can also be used for material and manufacturing run traceability and specifications confirmation.

The AIR STOP product has been validated and approved by international diesel engine manufacturers, including significant ‘shaker / vibration table’ testing, mule engine testing, and extended field testing. In addition, and in conjunction with engine rebuild cycles, valves have been inspected after 24000 hour ‘Frac engine’ field usage and remained fully functional. 

ENVACON AIR STOP valves; confirmed functionality and durability, even for the most severe engine applications.