What is the difference between a safety valve and a pressure relief valve?
We break down the differences between the two types of valves: pressure relief and safety valves
In the industrial and domestic fluid handling sector, pressure relief valves and safety valves are essential elements of defence and safety.
These elements are the last barrier between a serious accident or allowing everything to remain in optimum condition. But are safety valves and pressure relief valves the same, and how do they differ, and how is each used, questions that we will clarify below.
Are a safety relief valve and a pressure relief valve the same?
No. Although, these valves have the same purpose, to prevent overpressure, there are notable differences that suit different tasks. Therefore, they can both be adapted to the same process or work separately.
What is a safety relief valve?
The safety relief valve is a part that assists in the release of atmospheric pressure; or, in other words, it relieves the pressure outside a system. Thus, when the time comes, it will open fully and release the pressure, preventing an explosion.
What is a pressure relief valve?
A pressure relief valve, as the name suggests, maintains the fluid’s fluidity. So, it always seeks to maintain relief in the system and tries to keep the pressure down. So, if the pressure starts to increase gradually, the valve will also start to open gradually.
How is each valve used, and what is the difference in setting and capacity of each valve?
Regarding the use, the safety valve is more used in thermal systems and in those types of vessels that can release the pressure, accumulating the energy, to release it and restart, without the need to do it manually. Therefore, its use is more common with gases, hot fluids and chemicals.
The capacity of the safety relief valve, on the other hand, allows it to handle overpressure states; although, in some cases, it may require the help of an operator who closes or opens the valve, depending on a signal, to release the stress and continue normal operation.
The overflow valve (as the pressure relief valve is also known) is more commonly used in systems where the pressure remains static or continuous.
Thus, its operation is automatic; it will open only to release the pressure and not exceed the liquid force; therefore, its use is more common with fluids (although, they can also be used with vapours or moderate gases). In terms of capacity, they can withstand low pressures and their processes are continuous.
As soon as it detects that there is an excess pressure, it starts the opening process and keeps on working.
How are pressure relief valves and safety valves designed?
Although, they are pieces that are adjusted for different needs, depending on the design of the system, each valve has to meet certain criteria that standardize its reliability. In such a way, these types of valves must have:
Use of materials that can withstand high temperatures and overpressure
While, in some cases, they must be adaptable to fit different pipelines.
They must even be designed to work even with breaks. In such a way that it does not affect the flow and obstruct the discharge in the system.
What are the existing valve types of each (pressure relief and safety)?
There are three types of valves that can be found on the market:
Mechanical. Those with a plug that opens to release pressure, while an exhaust is used to release fluids. This type of valve employs a complex system that requires a spring to be calibrated and adjusted to a point that allows the fluid to be released at the required time. Pressure relief valves even employ a mechanism that facilitates opening at the exact moment a specific threshold is exceeded.
Electric valves. These are valves that make use of a pressure switch system to control the pressure. Thus, it is possible to control the times at which the solenoid valve must be triggered to release the required or specific pressure.
Electronic valves. These are a type of valve that uses a transducer to send signals to a control system. Thus, the system can decide when to open the solenoid valve, depending on the pressure that is concentrated.
What other features should be considered when purchasing a pressure or safety relief valve?
They must be capable of exceeding the rated pressure capacity (at least 110% higher).
They must also have the ability to operate above the temperature limit, thus ensuring that they can continue to operate even in extreme use.
Effective seal and stem guidance should be provided to avoid problems with expansion, contraction, and grease build-up.
It is preferable that they have a hand lever for opening, with a suitable design and that the weight (of this element) will not affect the operation.
They should have a safety system to prevent unauthorized tampering.
Why is it necessary to purchase a safety or pressure relief valve from a specialist?
The selection and installation of such a part is intended to prevent serious accidents and explosions. Thus, the correct selection and fitting depends on accurate decision-making, which is why it is always preferable to approach a specialist.
And one of the best options is Valfonta, who can adapt to any personal or industrial need. At Valfonta, we are specialists in pressure valves, so please do not hesitate to contact our sales department with any questions you may have. You can do so by completing our web form, by calling (+34) 93 372 08 88 or by sending an e-mail to firstname.lastname@example.org.
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