Boiler Blow-Down Valves | McMaster-Carr

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52 Products

About Flow-Adjustment Valves

About Gradual On/Off Valves

About Pressure-Relief Valves

About On/Off Valves

Threaded Gradual On/Off Valves for Boiler Blow-Off

Prevent boiler scale deposits and sediment buildup with these valves that meet ASME standards for boiler drainage applications. Also known as gate valves, they gradually open and close to prevent system damage from suddenly starting or stopping flow.

Valves with a wheel handle open and close with multiple turns, providing more controlled, shock-resistant flow than valves with a lever handle. Valves with a lever handle open and close faster than valves with a wheel handle.

Valves with a nonrising stem fit well in low-clearance places since the handle doesn’t move up when the valve opens.

Cast iron valves absorb vibration, reducing noise from your industrial boiler. Steel valves resist corroding from the dirt and particles that come out of industrial boilers better than cast iron valves.

Use repair kits to replace worn-out seals.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.

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

Wheel Handle and Nonrising Stem—Cast Iron Body and Gate

Valve Type: Gate
For Use With: Water
Packing Material: EPDM Rubber
Specifications Met: ASME B16.34, ASME B16.5, ASME B31.1, ASME BPVC.I

Valves
					O'all				Repair Kits
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Temp. Range, °F	End-to-End Lg.	Ht.	Lg.		Each		Each
NPT Female
1 1/4	60	250 psi @ 350° F	35° to 350°	3 5/8"	13"	9"	0000000	000000000	00000000	0000000
1 1/2	108	250 psi @ 350° F	35° to 350°	4 1/2"	13"	9 1/2"	0000000	00000000	00000000	000000
2	132	250 psi @ 350° F	35° to 350°	4 5/8"	14"	9 11/16"	0000000	00000000	00000000	000000

Lever Handle—Cast Iron Body and Gate

Valve Type: Gate
For Use With: Water
Packing Material: EPDM Rubber
Specifications Met: ASME B16.34, ASME B16.5, ASME B31.1, ASME BPVC.I

Valves
					O'all				Repair Kits
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Temp. Range, °F	End-to-End Lg.	Ht.	Lg.		Each		Each
NPT Female
1	40	250 psi @ 350° F	35° to 350°	3 5/8"	14 1/4"	4 7/16"	0000000	0000000	00000000	0000000
1 1/4	60	250 psi @ 350° F	35° to 350°	3 5/8"	13 1/16"	4 3/4"	0000000	000000	00000000	000000
1 1/2	108	250 psi @ 350° F	35° to 350°	4 1/2"	20 3/8"	5 13/16"	0000000	000000	00000000	000000
2	132	250 psi @ 350° F	35° to 350°	4 5/8"	21 5/16"	6 1/16"	0000000	00000000	00000000	000000

Lever Handle—Steel Body and Stainless Steel Gate

Valve Type: Gate
For Use With: Water
Packing Material: Graphite/TFE Plastic Blend
Specifications Met: ASME B16.34, ASME B16.5, ASME B31.1, ASME BPVC.I

Valves
					O'all				Repair Kits
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Temp. Range, °F	End-to-End Lg.	Ht.	Lg.		Each		Each
NPT Female
1 1/4	60	490 psi @ 750° F	35° to 750°	5 1/4"	13 1/8"	5 1/4"	00000000	000000000	00000000	0000000
1 1/2	108	490 psi @ 750° F	35° to 750°	6"	17 11/16"	6"	00000000	00000000	00000000	000000
2	132	490 psi @ 750° F	35° to 750°	6 1/4"	23 9/16"	6 1/4"	00000000	00000000	00000000	000000

Low-Pressure Threaded Flow-Adjustment Valves

Straight

90° Elbow

Valve Type: Globe
For Use With: Water
Specifications Met: See table

Use these valves for boiler maintenance and other low-pressure plumbing applications. They gradually open and close with multiple turns of the wheel handle to adjust and regulate flow. All have a rising stem that lifts as the valve opens and lowers as the valve closes to provide a visual indication of whether flow is on or off.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.

Bronze Body—Straight
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Temperature Range, °F	End-to-End Lg.	Port-to-Port Lg.	Stem Type	Specifications Met		Each
NPT Female × NPT Female
1/4	Not Rated	175 psi @ 90° F	-20° to 150°	2"	__	Rising	__	0000000	000000
3/8	Not Rated	175 psi @ 90° F	-20° to 150°	2"	__	Rising	__	0000000	00000
1/2	Not Rated	175 psi @ 90° F	-20° to 150°	2 5/16"	__	Rising	UL Listed	0000000	00000
3/4	Not Rated	175 psi @ 90° F	-20° to 150°	2 5/16"	__	Rising	UL Listed	0000000	00000
1	Not Rated	175 psi @ 90° F	-20° to 150°	3 1/8"	__	Rising	UL Listed	0000000	000000
1 1/4	20	175 psi @ 90° F	-20° to 150°	4 5/16"	__	Rising	UL Listed	000000	000000
1 1/2	28	175 psi @ 90° F	-20° to 150°	4 11/16"	__	Rising	UL Listed	0000000	000000
2	48	175 psi @ 90° F	-20° to 150°	5 5/8"	__	Rising	UL Listed	0000000	000000
Bronze Body—90° Elbow
NPT Female × NPT Female
1/2	Not Rated	175 psi @ 90° F	-20° to 150°	__	1 1/16"	Rising	UL Listed	0000000	00000
3/4	Not Rated	175 psi @ 90° F	-20° to 150°	__	1 3/16"	Rising	UL Listed	0000000	00000
1	Not Rated	175 psi @ 90° F	-20° to 150°	__	1 5/8"	Rising	UL Listed	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	000000
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

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

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

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	000000