Why should a steam safety valve be a type equipped with a wrench (A48Y)? Can’t a regular full-opening spring safety valve (A42Y) be used instead?
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Why should a steam safety valve be a type equipped with a wrench (A48Y)? Can’t a regular full-opening spring safety valve (A42Y) be used instead?
Safety valves are divided into two main types: spring-type and rod-type. There are also impulse-type safety valves, pilot-operated safety valves, safety switching valves, safety pressure relief valves, gravity-type safety valves, and others. Spring-loaded safety valves operate primarily by the force of a spring. There are two types of such valves: those with a sealed design and those without a sealed design. For media that are flammable, explosive, or toxic, a sealed design is generally preferred, while for steam or inert gases, an unsealed design can be used. Additionally, there are spring-loaded safety valves equipped with a wrench and those that do not. The main purpose of the wrench is to check the flexibility of the valve disc; it can also be used for manual emergency pressure relief.
There is no wrench for model 42, but it can be opened regularly for operation – how do you proceed? Take it off and send it to the metrology institute? One such fee is enough to buy a new valve. When considering a problem, both functionality and operability need to be taken into account.
The manufacturer’s explanation is as follows:
The text in the screenshot above explains very well why manual lifting is necessary and what the purpose of setting up manual lifting is.
Check the national standards regarding the numbering rules for safety valves; both safety valves of type (A48Y) and (A42Y) should be equipped with a manual lifting rod, although their pressure specifications differ.
Thank you! A44 comes with a wrench (closed valve cover), A48 comes with one (open valve cover), A42 comes without a wrench (closed valve cover).
The first digit 4 after A denotes a safety valve with a spring-loaded sealed mechanism and a wrench for full opening. Specified by JBT.