Liquid and Gas Safety Shutoff Valves
|Publication Date:||1 November 2016|
This standard sets performance requirements for liquid and gas safety shutoff valves, fire safe (class 7440) and non-fire safe (Class 7400), used in the supply lines of commercial and industrial burners as well as in ignitable liquid piping systems.
Safety shutoff valves are intended to either completely close or open in response to one or more of the following conditions: a remote safety shutdown signal, loss of actuating medium, or under the influence of heat.
Safety shutoff valves may be held open or closed electrically, pneumatically, hydraulically, mechanically or a combination of one or more of the aforementioned methods. The valve shall return to its normal position automatically in response to one or more of conditions described in Section 1.2.2. In general, automatic return is by means of a spring.
Safety shutoff valves shall reset manually, either locally or remotely.
Fire safe valves are intended to provide the same functionality as safety shutoff valves with the additional ability to minimize the total amount of internal and external valve leakage when exposed to fire conditions.
Process flow control valves are included in the scope of this standard when equipped with a safety shutoff feature that meets the standard requirements.
Valves without automatic operation are not covered in the scope of this Approval.
The requirements of this standard shall be used to measure and describe the performance of safety shutoff valves in response to exposure from heat, pressure, etc., under controlled laboratory conditions. The results of these controlled exposures shall not be used to describe or appraise actual exposure conditions since such conditions will vary widely.
This standard replaces the following Class Numbers:
• Class 7411 Safety Shutoff Valves - Electric Opening and Holding
• Class 7412 Safety Shutoff Valves - Electric and Pressure Opening and Holding
• Class 7413 Safety Shutoff Valves - Manual Opening, Electric Holding
• Class 7431 Emergency Automatic Shutoff Valves
• Class 7432 Emergency Quick-Opening Valves
• Class 7450 Process Flow Control Valves - Electric Opening
• Class 7451 Process Flow Control Valves - Combination Electric & Pressure Opening
• Class 7452 Process Flow Control Valves - Pressure Opening
• Class 7453 Process Flow Control Valves - Manual
This standard states Approval requirements for liquid and gas safety shutoff valves including those classified as fire safe valves.
Approval criteria may include, but are not limited to, performance requirements, marking requirements, examination of manufacturing facility(ies), audit of quality assurance procedures, and a follow-up program.