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Safety relief valve: essential on pressure systems
Safety relief valves are the last point of protection in pressurised systems, prior to excess pressure incidents which could be disasters: safety relief valves automatically vent excess vapour and gas
Automatic venting occurs once the adjusted opening pressure is reached.
A spring or weight loaded element in the valve yields and opens to vent excess pressure.
For example, when the maximum permissible operating pressure of the system has been reached.
Once the pressure has been equalised, the valve closes automatically, and would activate once again with a further increase in pressure.
There are two types: controlled safety relief valves offer more precise behaviour compared to direct acting safety relief valves, but are more complex and usually more expensive.
Spring loaded direct acting safety relief valves have therefore become more common in practice.
In selection of the right valve consideration must be given to the type of gas together with the opening pressure, temperature range and inlet connection.
Where applicable, an optional condensation outlet may be required to discharge moisture.
In corrosive operating conditions, the valve should be stainless steel rather than brass.
Safety relief valves must be certified according to a design specification.
The most important standards are the Pressure Equipment Directive 97/23/EC and the European standard EN ISO 4126-1.
These are equipment components with a safety function so that the functional quality is of particular importance.
For piece of mind, it is best to choose known brands, such as the products manufactured by the German manufacturer Witt.
Safety relief valves made by Witt are not only suitable for all technical gases they can also be mounted in any position/orientation.
They are individually tested by TUV and certified accordingly.
That ensures operational safety and facilitates official approval of the complete system.
A version is available with a vent option that facilitates the function test, which is a mandatory test in many countries.
The follwoing is a report of a safety relief valve background interview with Christian Flucken, sales manager for safety relief valves at Witt-Gasetechnik, Germany.
Q: Witt is known as a manufacturer of gas safety and gas control equipment.
What role do safety relief valves play in your product range?.
A: Safety relief valves are very important for operators of technical gas systems: their absence jeopardises the safety of man and machines.
Witt offer a full range of gas safety equipment and safety relief valves compliment our range of high quality equipment.
Q: Why does Witt concentrate on certain models?.
A: There's a saying: don't experiment with safety! This is why Witt have concentrated on spring loaded safety relief valves.
The pressure equipment market is certainly one of our prime markets.
In future, we want to expand the portfolio in every direction with new technology.
Additions will include low-temperature safety valves and overflow valves.
We are more than qualified to offer solutions to suit special applications.
Q: In contrast to other manufacturers, you have every valve tested by TUV.
Why?.
A: Witt is taken as a synonym for safety and reliability.
Strict quality principles and controls account for a large share of our success.
Examples: our goods receipt inspection processes include tests for dimensionally accurate production.
Prior to assembly we test every pressure-bearing part for strength and tightness.
At final inspection, every single valve has to pass a leak and function test.
We simply want to set standards when it comes to quality, and the objective inspectors at TUV underline our own performance promise.
The user reaps double benefit: the certificate also makes it easier to obtain approval for his complete system.
Q: Could users manage without safety relief valves completely?.
A: In most cases, a safety valve is not only mandatory by law but it also acts as an overflow valve.
In closed containers with excess pressure, it constitutes the "last resort" before the system over pressurises.
Installing safety relief valves in a system is of significant importance.
Not only does it remove the risk of production issues, but lives can be saved.
Sent: 12/06/2008
Email us direct at: repairs@londonheatingservices.co.uk
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