Do weather and temperature affect valve performance?

Yes, they can. For example, high ambient temperatures can affect the set pressure of the valve, whereas low ambient temperatures (combined with moisture) can make valves freeze, leading to possible malfunction.

What mounting orientation should be used to install a Watts relief valve?

We recommended vertically installing the valve. This way, it can be ensured that the valve body is self-draining and that set pressure is achieved. If the safety valve is installed in any position other than vertical and upright, it may adversely affect its performance and lifespan.

What should I check during visual inspection of a relief valve?

Clogged drains and discharge pipesDirt build-up around the seat Broken, damaged or missing parts and seals

What causes a relief valve to fail?

Contaminants like dirt / lint / rust / sludge, or misalignment of the valve can cause it to stick and not function properly.

What is the difference between orifice and inlet size?

The orifice diameter is the diameter of the internal opening of the valve, which is used to determine the flow capacity. Inlet size refers to the interface of the valve or the size / type of the threads where you attach it.

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WATTS Safety Relief Valve, Bronze

Safety relief valves, also known as pressure relief valves, open when a preset pressure point is reached and release fluid until the pressure drops to an acceptable level. These valves control or limit the pressure in a system. This is necessary because pressure could build up and disrupt a pro...cess, cause instrument failure or start a fire. Watts relief valves (174A Series) are used to prevent the build-up of pressure in a wide range of applications involving water, oil and air.Read more

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Body Material: Bronze , Inlet Type: FNPT , Outlet Type: FNPT , Pressure Range: 30 to 150 psi , Temp. Range: 0 Degrees to 250 Degrees F , Test Lever: Yes

Style	Model	Overall Height	Seat Material	BtuH	Overall Length	Disc Material	Spring Material	Factory Set Pressure	Inlet Size	Price (ex. VAT)
A	1 174A 125	5.75"	Metal	3,215,000	3"	Nonmetallic	Stainless Steel	125 psi	1"	€342.65
A	1 174A 100	5.75"	Metal	2,635,000	3"	Nonmetallic	Stainless Steel	100 psi	1"	€344.65
A	1 174A 75	5.75"	Metal	2,055,000	3"	Nonmetallic	Stainless Steel	75 psi	1"	€423.89
B	1 174A-050	5.75"	Bronze	1,470,000	3"	Silicone	Stainless Steel	50 psi	1"	€455.45
C	1 174A-150	5.75"	Bronze	3,795,000	3"	Silicone	Stainless Steel	150 psi	1"	€456.92
D	3/4 174A-075	5.125"	Bronze	1,320,000	2.5"	Silicone	Stainless Steel	75 psi	3/4"	€177.57
E	174 A-3/4"	5.125"	Metal	650,000	2.5"	Nonmetallic	Stainless Steel	30 psi	3/4"	€105.74
D	3/4 174A-050	5.125"	Bronze	950,000	2.5"	Silicone	Stainless Steel	50 psi	3/4"	€167.24
D	3/4 174A-125	5.125"	Bronze	2,070,000	2.5"	Silicone	Stainless Steel	125 psi	3/4"	€178.07
D	3/4 174A-150	5.125"	Bronze	2,445,000	2.5"	Silicone	Stainless Steel	150 psi	3/4"	€172.95
D	3/4 174A-100	5.125"	Bronze	1,695,000	2.5"	Silicone	Stainless Steel	100 psi	3/4"	€178.01
B	1 1/4 174A-075	8.375"	Bronze	3,429,000	4.75"	Silicone	Stainless Steel	75 psi	1.25"	€757.71
B	1 1/4 174A-100	8.375"	Bronze	4,399,000	4.75"	Silicone	Stainless Steel	100 psi	1.25"	€786.31
B	1 1/4 174A-125	8.375"	Bronze	5,370,000	4.75"	Silicone	Stainless Steel	125 psi	1.25"	€810.14
B	1 1/4 174A-150	8.375"	Bronze	6,340,000	4.75"	Silicone	Stainless Steel	150 psi	1.25"	€714.83
F	11/4 174 A	8.375"	Metal	1,682,000	4.75"	Buna-N	Brass	30 psi	1.25"	€559.23
B	1 1/2 174A-150	9"	Bronze	7,630,000	4.875"	Silicone	Stainless Steel	150 psi	1.5"	€1,196.30
G	2 174A-050	11.625"	Bronze	5,575,000	6.25"	Silicone	Stainless Steel	50 psi	2"	€1,459.26
D	2 174A-075	11.625"	Bronze	7,770,000	6.25"	Silicone	Stainless Steel	75 psi	2"	€1,459.26
D	2 174A-100	11.625"	Bronze	9,970,000	6.25"	Silicone	Stainless Steel	100 psi	2"	€1,697.89
D	2 174A-125	11.625"	Bronze	12,170,000	6.25"	Silicone	Stainless Steel	125 psi	2"	€1,697.89
D	2 174A-150	11.625"	Bronze	14,370,000	6.25"	Silicone	Stainless Steel	150 psi	2"	€1,379.02
F	2 174 A	11.625"	Metal	3,815,000	6.25"	Buna-N	Brass	30 psi	2"	€1,242.39

Working Mechanism

Watts relief valves are installed after the pump in hydraulic systems, since they reduce pressure equal to their spring settings.
These 174A relief valves open when a backpressure or downstream load exerts enough pressure to open the poppet or spool against its spring.
They provide excessively pressurised fluid with an open path to the tank, with the goal of reducing work port pressure.
As fluid pressure begins to rise, the force from that pressure is applied to the bottom of the spool or poppet.
The relief valve opens modestly at first, bleeding as little fluid as required to maintain pressure downstream.
The poppet or spool pushes further against the spring as downstream pressure rises so that it is equalised with hydraulic force.

Features

Watts 174A Series relief valves are used to protect against excessive pressure in hot water heating equipment.
They feature bronze body construction, NPT threaded female inlet & outlet (drain) connections, non-metallic disc-to-metal seating, a stainless steel spring and a test lever for ease of operation.
Watts 174A relief valves are resistant to corrosive water conditions, sticking and freezing. They also prevent water and sediments from accumulating in the seat.
They are ideal for emergency safety relief and should not be used as operating control valves.

Standards and Approvals

ASME Section IV