Boiler Safety Valves | McMaster-Carr

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About Pressure-Relief Valves

Valve With Test Lever

Valve With Swivel Test Lever

For Use With: Steam
Temperature Range: -60° to 400° F

These valves meet ASME Code Section I for use with steam power boilers requiring pressure relief above 15 psi. They spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. For remote discharge, attach a drain line to the threaded relief port. Valves have a durable bronze body for a long service life.

EPR rubber seals provide better leak protection than brass seals.

Swivel test levers rotate 360° around the valve for use in areas with limited clearance.

For technical drawings and 3-D models, click on a part number.

Inlet			Relief Port
Pipe Size	Location	Maximum Pressure, psi	Pipe Size	Location	Overall Ht.	Test Mechanism	Test Lever Type	Valve Type	Specifications Met	Choose a Set Pressure, psi		Each
NPT Male Inlet and NPT Female Relief Port
Bronze Body—Brass Seal
1/2	Bottom	250	3/4	Side	6 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	0000000
1/2	Bottom	250	3/4	Side	7 5/16"	Lever	Swivel	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
3/4	Bottom	250	1	Side	7 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
3/4	Bottom	250	3/4	Side	7 5/16"	Lever	Swivel	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1	Bottom	250	1	Side	7 5/8"	Lever	Swivel	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1	Bottom	250	1 1/4	Side	8 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1 1/4	Bottom	250	1 1/2	Side	9 5/8"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1 1/2	Bottom	250	1 1/2	Side	9 5/8"	Lever	Swivel	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1 1/2	Bottom	250	2	Side	10 5/8"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
2	Bottom	250	2 1/2	Side	13 5/8"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
Bronze Body—EPR Seal
1/2	Bottom	250	3/4	Side	6 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
3/4	Bottom	250	1	Side	7 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000
1	Bottom	250	1 1/4	Side	8 1/2"	Lever	__	Pop Safety	ASME BPVC.I	15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250	0000000	000000

ASME-Code Fast-Acting Pressure-Relief Valves for Low-Pressure Steam

For Use With: Steam
Specifications Met: ASME BPVC.IV
Max. Temperature: 250° F

For use with low-pressure steam-heating boilers requiring pressure relief at 15 psi, these valves meet ASME Code Section IV. All spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. Body is bronze for durability and a long service life.

Vented relief ports exhaust discharge directly.

Threaded relief ports can be attached to a drain line for remote discharge.

For technical drawings and 3-D models, click on a part number.

Straight

Inlet				Relief Port
Pipe Size	Connection	Location	Maximum Pressure, psi	Connection Type	Location	Steam Flow Capacity, lbs./hr.	Set Pressure, psi	Overall Ht.	Test Mechanism	Valve Type		Each
Bronze Body—EPDM Seal
3/4	NPT Male	Bottom	15	Vent	Top	410	15	2 7/8"	Lever	Pop Safety	0000000	000000

Elbow

Inlet				Relief Port
Pipe Size	Connection	Location	Maximum Pressure, psi	Pipe Size	Connection	Location	Steam Flow Capacity, lbs./hr.	Set Pressure, psi	Overall Ht.	Test Mechanism	Valve Type		Each
Bronze Body—PTFE-Coated EPDM Seal
3/4	NPT Male	Bottom	15	3/4	NPT Female	Side	470	15	3 13/16"	Lever	Pop Safety	0000000	000000
1	NPT Male	Bottom	15	1	NPT Female	Side	640	15	4"	Lever	Pop Safety	0000000	00000
1 1/4	NPT Male	Bottom	15	1 1/2	NPT Female	Side	1,200	15	4 1/2"	Lever	Pop Safety	0000000	000000
1 1/2	NPT Male	Bottom	15	2	NPT Female	Side	1,900	15	5 1/4"	Lever	Pop Safety	0000000	000000
2	NPT Male	Bottom	15	2	NPT Female	Side	2,500	15	6 9/16"	Lever	Pop Safety	000000	000000
2 1/2	NPT Male	Bottom	15	2 1/2	NPT Female	Side	3,520	15	8 1/8"	Lever	Pop Safety	000000	000000
3	NPT Male	Bottom	15	3	NPT Female	Side	4,100	15	9 1/16"	Lever	Pop Safety	000000	000000

Fast-Acting Pressure-Relief Valves for Ultra-Low-Pressure Steam

For Use With: Steam
Max. Temperature: 250° F

Choose these valves for small steam-heating boilers requiring pressure relief between 5 psi and 12 psi. They spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. All have a bronze body for durability and a long service life.

Vented relief ports exhaust discharge directly.

Threaded relief ports can be attached to a drain line for remote discharge.

For technical drawings and 3-D models, click on a part number.

Straight

Inlet			Relief Port
Pipe Size	Connection	Location	Connection Type	Location	Overall Ht.	Test Mechanism	Valve Type	Choose a Set Pressure, psi		Each
Bronze Body—EPDM Seal
3/4	NPT Male	Bottom	Vent	Top	2 7/8"	Lever	Pop Safety	5, 6, 8, 10, 12	0000000	000000

Elbow

Inlet			Relief Port
Pipe Size	Connection	Location	Pipe Size	Connection	Location	Overall Ht.	Test Mechanism	Valve Type	Choose a Set Pressure, psi		Each
Bronze Body—EPDM Seal
3/4	NPT Male	Bottom	3/4	NPT Female	Side	3 13/16"	Lever	Pop Safety	5, 6, 8, 10, 12	0000000	000000
1	NPT Male	Bottom	1	NPT Female	Side	4"	Lever	Pop Safety	5, 6, 8, 10, 12	0000000	00000

ASME-Code Fast-Acting Pressure-Relief Valves for Hot Water

For Use With: Water
Specifications Met: ASME BPVC.IV
Temperature Range: 33° to 250° F

Protect your water-heating system with these valves that meet ASME Code Section IV for hot water heaters and boilers. They spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. All have a threaded relief port that can be attached to a drain line for remote discharge. Valves have a durable bronze body for a long service life.

For technical drawings and 3-D models, click on a part number.

Inlet		Relief Port
Pipe Size	Location	Pipe Size	Location	Overall Ht.	Test Mechanism	Valve Type	Choose a Set Pressure, psi		Each
NPT Female Inlet and Relief Port
Bronze Body—Silicone Seal
3/4	Bottom	3/4	Side	5 5/16"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	0000000
3/4	Bottom	1	Side	5 5/16"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000
1	Bottom	1	Side	6 3/4"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000
1	Bottom	1 1/4	Side	6 3/4"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000
1 1/4	Bottom	1 1/2	Side	8 3/8"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000
1 1/2	Bottom	2	Side	10 13/16"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000
2	Bottom	2	Side	14"	Lever	Pop Safety	30, 50, 60, 75, 100, 125, 150	0000000	000000

ASME-Code Fast-Acting Pressure-Relief Valves for Water

For Use With: Water
Temperature Range: -60° to 406° F

These valves meet ASME Code Section VIII for use with water pressure vessels. They spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. All have a threaded relief port that can be attached to a drain line for remote discharge. Body is bronze for durability and a long service life.

For technical drawings and 3-D models, click on a part number.

Inlet		Relief Port
Pipe Size	Location	Pipe Size	Location	Overall Ht.	Valve Type	Specifications Met	Choose a Set Pressure, psi		Each
NPT Male Inlet and NPT Female Relief Port
Bronze Body—316 Stainless Steel Seal
1/2	Bottom	3/4	Side	7 1/2"	Pop Safety	ASME BPVC.VIII	20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300	0000000	0000000
3/4	Bottom	3/4	Side	7 1/2"	Pop Safety	ASME BPVC.VIII	20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300	0000000	000000
1	Bottom	1 1/4	Side	9"	Pop Safety	ASME BPVC.VIII	20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300	0000000	000000
1 1/2	Bottom	2	Side	13 1/4"	Pop Safety	ASME BPVC.VIII	20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300	0000000	000000

Fast-Acting Temperature- and Pressure-Relief Valves for Hot Water

Female × Female

Male × Female

Male × Female With Extended Body

For Use With: Water
Specifications Met:
Pipe size of 3/4-2: ASME BPVC.IV
Pipe size of 1/2-2: CSA Certified
Max. Temperature: 210° F

Also known as T & P valves, these open when water temperature reaches 210° F or at the set pressure. They are commonly used with water heaters and storage tanks. All spring fully open at a water temperature of 210° F or the set pressure and remain open until the system is restored below the set point. For remote discharge, valves have a threaded relief port to attach a drain line. Body is bronze for durability and a long service life.

Valves with 3/4 to 2 pipe size meet ASME Code Section IV for hot water.

Valves with an extended body are designed for installation through thick insulation.

For technical drawings and 3-D models, click on a part number.

Inlet			Relief Port		Set
Pipe Size	Location	Maximum Pressure, psi	Pipe Size	Location	Pressure	Temperature, °F	Water Flow Capacity, Btu/hr.	Features	Fits Insulation Thick.	Insertion Lg.	Valve Ht.	Overall Ht.	Test Mechanism	Valve Type		Each
NPT Female Inlet and NPT Female Relief Port
Bronze Body—Silicone Seal
3/4	Bottom	125	3/4	Side	125	210°	185,000	__	__	3"	5 7/8"	8 7/8"	Lever	Pop Safety	0000000	0000000
3/4	Bottom	150	3/4	Side	150	210°	185,000	__	__	3"	5 7/8"	8 7/8"	Lever	Pop Safety	0000000	000000
NPT Male Inlet and NPT Female Relief Port
Bronze Body—Silicone Seal
1/2	Bottom	150	1/2	Side	150	210°	15,000	__	__	1 7/16"	3 1/4"	4 11/16"	Lever	Pop Safety	0000000	00000
3/4	Bottom	150	3/4	Side	150	210°	95,000	__	__	1 7/16"	3 1/4"	4 11/16"	Lever	Pop Safety	0000000	00000
3/4	Bottom	150	3/4	Side	150	210°	105,000	__	__	3"	3 1/4"	6 1/4"	Lever	Pop Safety	0000000	00000
3/4	Bottom	165	3/4	Side	150	210°	105,000	Extended Body	1 1/4"	2 1/2"	4 3/4"	7 1/4"	Lever	Pop Safety	0000000	00000
3/4	Bottom	165	3/4	Side	150	210°	1,438,000	Extended Body	1 5/8"	3 1/2"	6 5/8"	10 1/8"	Lever	Pop Safety	0000000	000000
3/4	Bottom	165	3/4	Side	150	210°	1,438,000	Extended Body	3 5/8"	5"	8 5/8"	13 5/8"	Lever	Pop Safety	0000000	000000
1	Bottom	165	1	Side	150	210°	2,135,000	__	__	2"	6 1/4"	8 1/4"	Lever	Pop Safety	0000000	000000
1	Bottom	165	1	Side	150	210°	2,135,000	__	__	4"	6 1/4"	10 1/4"	Lever	Pop Safety	0000000	000000
2	Bottom	150	1 1/2	Side	150	210°	1,200,000	__	__	3"	8 1/2"	11 1/2"	Lever	Pop Safety	0000000	000000

Fast-Acting Pressure-Relief Valves for Air and Inert Gas

Valve

Valve With Test Lever

Valve
With
Test Ring

For Use With: Air, Inert Gas
Temperature Range: -30° to 400° F

These valves spring fully open at the set pressure and remain open until the system pressure is restored below the set pressure. They have a vented relief port to exhaust discharge directly.

For technical drawings and 3-D models, click on a part number.

Inlet
Pipe Size	Location	Maximum Pressure, psi	Relief Port Location	Overall Ht.	Test Mechanism	Valve Type	Choose a Set Pressure, psi		Each
NPT Male Inlet and Relief Vent
Brass Body and Seal
1/8	Bottom	100	Side	1 3/4"	__	Pop Safety	5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100	000000	000000
1/4	Bottom	200	Top	3 1/8"	Lever	Pop Safety	5, 10	0000000	00000
1/4	Bottom	300	Side	2 1/2"	__	Pop Safety	5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100	000000	00000
1/4	Bottom	300	Side	3 1/8"	Ring	Pop Safety	10, 15, 20	0000000	00000
3/8	Bottom	200	Top	3 1/8"	Lever	Pop Safety	5, 10	0000000	00000
3/8	Bottom	300	Side	2 1/2"	__	Pop Safety	5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100	000000	00000
3/8	Bottom	300	Side	3 1/8"	Ring	Pop Safety	10, 15, 20	0000000	00000
1/2	Bottom	200	Top	3 1/8"	Lever	Pop Safety	5, 10	0000000	00000
1/2	Bottom	300	Side	2 5/8"	__	Pop Safety	5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100	000000	00000
1/2	Bottom	300	Side	3 3/4"	Ring	Pop Safety	10, 15, 20	0000000	00000
3/4	Bottom	300	Side	5 7/16"	Ring	Pop Safety	10, 15, 20	0000000	000000
1	Bottom	300	Side	5 3/4"	Ring	Pop Safety	10, 15, 20	0000000	000000

Heat-Activated Threaded Pressure-Relief Discs

Also known as fusible plugs, these discs have a metal core that melts at a set temperature to exhaust discharge directly and allow unrestricted flow. Install these one-time-use discs in pipelines and tanks.

Exceeding the maximum operating temperature decreases service life and may cause the disc to open below its melting temperature. These discs should not be used in a system with an operating pressure greater than 500 psi.

Inlet
Pipe Size	Location	Relief Port Location	Max. Pressure, psi	Max. Operating Temperature, °F	Overall Ht.	Disc Material	Valve Type		Each
NPT Male Inlet and Relief Vent
Brass Body—165° F Melting Temperature
1/4	Bottom	Top	500	100°	3/4"	Bismuth, Cadmium, Lead, Tin	Rupture Disc	0000000	000000
3/8	Bottom	Top	500	100°	3/4"	Bismuth, Cadmium, Lead, Tin	Rupture Disc	0000000	00000
1/2	Bottom	Top	500	100°	7/8"	Bismuth, Cadmium, Lead, Tin	Rupture Disc	0000000	00000
Brass Body—212° F Melting Temperature
1/4	Bottom	Top	500	150°	3/4"	Bismuth, Lead, Tin	Rupture Disc	0000000	00000
3/8	Bottom	Top	500	150°	3/4"	Bismuth, Lead, Tin	Rupture Disc	0000000	00000
1/2	Bottom	Top	500	150°	7/8"	Bismuth, Lead, Tin	Rupture Disc	0000000	00000

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About Pressure-Relief Valves

ASME-Code Fast-Acting Pressure-Relief Valves for Steam

ASME-Code Fast-Acting Pressure-Relief Valves for Low-Pressure Steam

Fast-Acting Pressure-Relief Valves for Ultra-Low-Pressure Steam

ASME-Code Fast-Acting Pressure-Relief Valves for Hot Water

ASME-Code Fast-Acting Pressure-Relief Valves for Water

Fast-Acting Temperature- and Pressure-Relief Valves for Hot Water

Fast-Acting Pressure-Relief Valves for Air and Inert Gas

Heat-Activated Threaded Pressure-Relief Discs