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 ...Read More

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WATTS 3/4 174A-050A
WATTS 1 1/4 174A-125B
WATTS 2 174A-050C
WATTS 1 174A-150D
WATTS 174 A-3/4E
WATTS 11/4 174 AF
WATTS 1 174A 75G
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
StyleModelSeat MaterialBtuHDisc MaterialSpring MaterialFactory Set PressureInlet SizeOutlet SizeOverall HeightPrice (inc. GST)
A
3/4 174A-050		Bronze950,000SiliconeStainless Steel50 psi3/4"3/4"5.125" SGD 257.81
B
1 1/4 174A-125		Bronze5,370,000SiliconeStainless Steel125 psi1.25"1.25"8.375" SGD 1,172.31
A
2 174A-150		Bronze14,370,000SiliconeStainless Steel150 psi2"2"11.625" SGD 2,217.22
A
2 174A-125		Bronze12,170,000SiliconeStainless Steel125 psi2"2"11.625" SGD 2,456.92
A
2 174A-100		Bronze9,970,000SiliconeStainless Steel100 psi2"2"11.625" SGD 2,456.92
A
2 174A-075		Bronze7,770,000SiliconeStainless Steel75 psi2"2"11.625" SGD 2,111.62
C
2 174A-050		Bronze5,575,000SiliconeStainless Steel50 psi2"2"11.625" SGD 2,111.62
A
3/4 174A-075		Bronze1,320,000SiliconeStainless Steel75 psi3/4"3/4"5.125" SGD 257.67
B
1 1/2 174A-150		Bronze7,630,000SiliconeStainless Steel150 psi1.5"1.5"9" SGD 1,731.11
B
1 1/4 174A-100		Bronze4,399,000SiliconeStainless Steel100 psi1.25"1.25"8.375" SGD 1,264.26
B
1 1/4 174A-075		Bronze3,429,000SiliconeStainless Steel75 psi1.25"1.25"8.375" SGD 1,218.26
B
1 1/4 174A-150		Bronze6,340,000SiliconeStainless Steel150 psi1.25"1.25"8.375" SGD 1,149.31
D
1 174A-150		Bronze3,795,000SiliconeStainless Steel150 psi1"1"5.75" SGD 734.65
B
1 174A-050		Bronze1,470,000SiliconeStainless Steel50 psi1"1"5.75" SGD 732.30
A
3/4 174A-150		Bronze2,445,000SiliconeStainless Steel150 psi3/4"3/4"5.125" SGD 257.67
A
3/4 174A-125		Bronze2,070,000SiliconeStainless Steel125 psi3/4"3/4"5.125" SGD 257.67
A
3/4 174A-100		Bronze1,695,000SiliconeStainless Steel100 psi3/4"3/4"5.125" SGD 257.59
E
174 A-3/4"		Metal650,000NonmetallicStainless Steel30 psi3/4"3/4"5.125" SGD 170.00
F
11/4 174 A		Metal1,682,000Buna-NBrass30 psi1.25"1.25"8.375" SGD 899.14
F
2 174 A		Metal3,815,000Buna-NBrass30 psi2"2"11.625" SGD 1,997.54
G
1 174A 75		Metal2,055,000NonmetallicStainless Steel75 psi1"1"5.75" SGD 613.38
G
1 174A 100		Metal2,635,000NonmetallicStainless Steel100 psi1"1"5.75" SGD 554.14
G
1 174A 125		Metal3,215,000NonmetallicStainless Steel125 psi1"1"5.75" SGD 550.93

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

Frequently Asked Questions

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 pipes
  • Dirt 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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