Can I use a Conbraco Series 10 hot water relief valve on a steam boiler?

No. Conbraco Series 10-600 valves are ASME Section IV certified for hot water heating service only and are not designed or approved for steam boiler service. For low pressure steam heating boilers (5–15 PSI), use Conbraco Series 13 (3/4" to 1-1/2") or Series 12-200 (2" to 3"). For power boilers or unfired pressure vessels, use Conbraco Series 19 (ASME Section I or Section VIII). Installing a hot water relief valve on a steam boiler is a code violation and a safety hazard — steam service requires a pop-action valve specifically certified for steam at the correct set pressure and capacity.

What is the correct installation for a Conbraco Series 10-600 relief valve?

Per Conbraco's official installation instructions (IOM ES1325): the valve must be mounted in a vertical upright position, directly to a clean tapped opening in the top of the pressure vessel. There must be no flow restriction, check valve, or shutoff valve of any type between the relief valve and the pressure vessel. A discharge line must be piped from the valve outlet to a safe point of discharge — no intervening valve, independently supported, pitched to drain, no smaller than the valve outlet size, terminating freely to atmosphere, and with a plain (unthreaded) end. Do not use pipe wrenches — use proper wrenches on wrench pads only. Do not use this valve on coal or wood-fired boilers with uncontrolled heat input. Contact us at (901) 458-2000 for installation guidance.

Conbraco / Apollo Valves · Made in USA since 1928 · Aalberts Industries · Memphis, TN

Conbraco / Apollo Valves —
Series 10 Hot Water Relief, Steam Safety Valves, Gauges & Ball Valves

Q: What is the difference between Conbraco Series 10, Series 12/13, and Series 19 relief valves?

Series 10-600: Hot water boiler safety relief valves — ASME Section IV (HV stamp), 15–160 PSI, hot water service only. Not for steam boiler service. National Board capacity certified. Series 13 (3/4"–1-1/2") and Series 12-200 (2"–3"): Low pressure steam safety valves — ASME Section IV (HV stamp), 5–15 PSI, for low pressure steam heating boilers. Steam service only — not for hot water boiler service. Registered in all Canadian provinces and territories, CRN #0G8547.5C. Series 19: Industrial full-nozzle safety relief valves — ASME Section I (V stamp, power boilers) and Section VIII (UV stamp, unfired pressure vessels), 15 to 1,200 PSI, in steam, air/gas, and liquid service configurations. Selecting the wrong series for your service type is a code violation and a safety hazard. Call (901) 458-2000 with your boiler type and nameplate data.

Q: How do I size a Conbraco hot water boiler relief valve?

Two requirements must both be met. First: the set pressure of the valve must not exceed the boiler's maximum allowable working pressure (MAWP) stamped on the boiler nameplate. Second: the BTU/hr discharge capacity of the valve (stamped on the valve nameplate and listed in the product description) must equal or exceed the boiler's BTU input rating. Additionally, Conbraco recommends maintaining a minimum operating pressure margin of at least 10 PSI or 25% of the set pressure (whichever is greater) between the system's normal operating pressure and the valve's set pressure. Insufficient margin causes the valve to simmer and leak, depositing minerals on the seat. For example: a boiler with a 30 PSI MAWP, 2,000,000 BTU input, and 20 PSI normal operating pressure needs a valve set at 30 PSI with at least 2,000,000 BTU capacity, and the 10 PSI margin (30 PSI set minus 20 PSI operating) is satisfied. Call (901) 458-2000 with your boiler make, model, BTU input, MAWP, and normal operating pressure for sizing help.

Q: What does National Board capacity certified mean on a Conbraco relief valve?

National Board capacity certification means the BTU/hr (or lb/hr steam) discharge capacity stamped on the valve nameplate has been independently tested and certified by the National Board of Boiler and Pressure Vessel Inspectors — not just calculated or factory-claimed. Conbraco states that National Board ratings are 90% of actual capacity at 10% overpressure, per standard ASME certification methodology. All Conbraco safety and relief valves are 100% factory tested before shipment at ASME-certified setting stations. The ASME HV symbol on the nameplate confirms Section IV compliance for heating boilers. The NB symbol confirms National Board capacity certification. CRN on the nameplate is the Canadian Registration Number (CRN #0G8547.5C for most Conbraco ASME Section IV valves), confirming registration in all Canadian provinces and territories.

Q: Should I replace a relief valve that has discharged?

Yes — any relief valve that has opened under pressure should be replaced, not returned to service. When a valve discharges, the high-velocity flow can damage the seat and disc surfaces. A valve that appears to re-close after discharging may leak slowly or fail to open at the correct set pressure in the future. The standard code and Conbraco manufacturer guidance is to replace the valve after any discharge event. Call (901) 458-2000 with your existing part number and we will source the correct Conbraco replacement.

Memphis Control Center stocks and special-orders Conbraco relief valves and flow control products — marketed under the Apollo Valves brand — for commercial and industrial boiler, hydronic, steam, and piping applications. Series 10-600 hot water boiler safety relief valves (ASME Section IV, HV stamp, National Board certified, 15–160 PSI, 3/4"–2", hot water service only, ASTM B584 bronze, 100% factory tested). Series 13 and 12 low pressure steam safety valves (ASME Section IV, 5–15 PSI, registered in all Canadian provinces and territories, CRN #0G8547.5C). Series 19 industrial safety relief valves (ASME Section I and VIII, V and UV stamp, to 1,200 PSI, steam/air/gas/liquid). Liquid level gauges (Series 20, 24, 25) and Apollo ball valves (70 Series, 76, 77CLF, 82LF). Conbraco has manufactured flow control products in the USA since 1928, with plants in Pageland and Conway, South Carolina. All plants are ISO 9001 certified. Free same-day shipping on stocked items from Memphis, TN.

Browse All Conbraco Products Call (901) 458-2000

Made in USA since 1928 ISO 9001 All Plants ASME Section I · IV · VIII 100% Factory Tested · NB Certified 2,574 Products

ASME HV · V · UV StampsASME Section IV (HV — heating boilers), Section I (V — power boilers), Section VIII (UV — unfired pressure vessels). National Board capacity certified.

100% Factory TestedEvery Conbraco safety and relief valve is 100% factory tested before shipment at ASME-certified setting stations

Made in USA since 1928Conbraco has manufactured flow control products in the USA since 1928 — plants in Pageland and Conway, SC, ISO 9001 certified

Same-Day ShippingStocked items ship same day from Memphis, TN — free. Call (901) 458-2000 for special order lead times

Conbraco Industries, Inc. — nearly 100 years of American manufacturing. On April 24, 1928, American Lubricator and Brass Co. and Sterling & Skinner Manufacturing Co. merged in Detroit to form Consolidated Brass Company. The company planned its southern expansion in 1955 and completed the move to its Charlotte, NC headquarters, plant and foundry in 1960. It expanded to Pageland, SC in 1968 — the same year the Apollo 70 Series ball valve was introduced to the commercial market — and to Conway, SC in 1982. In 1977 the company became Conbraco Industries, Inc. In June 2010, Dutch global technology company Aalberts Industries acquired Conbraco. Today, all Conbraco products are marketed under the Apollo Valves brand, with headquarters in Matthews, North Carolina (701 Matthews Mint Hill Road, Matthews, NC 28105; mailing: P.O. Box 247). The Apollo 70 Series ball valve has sold more than 150 million units and remains one of the most-specified ball valves in the industry.

Conbraco / Apollo Valves — Product Lines at Memphis Control Center

All Conbraco safety and relief valves are 100% factory tested and National Board capacity certified. Contact us or call (901) 458-2000 with your boiler type (hot water or steam), BTU input rating, inlet size, and the MAWP stamped on your boiler nameplate.

Series 10-600 Series 10-600 — Hot Water Boiler Safety Relief Valves

The Conbraco Series 10-600 (Apollo 10-600) is a family of ASME Section IV (HV stamp) hot water boiler safety relief valves for commercial and industrial hot water heating systems. Hot water service only — not for steam boiler service. National Board capacity certified at all pressure settings. 100% factory tested.

Construction: ASTM B584 bronze body and nozzle. Stainless steel spring. Silicone seat. Elevated seat design — drainage channel prevents water accumulation at seat area. Fabric-reinforced molded diaphragm isolates the spring chamber from system water, preventing mineral scaling on spring internals. Lift lever included for manual testing. Must be mounted vertically upright, direct to tapped opening in pressure vessel — no valve between relief valve and vessel.

Specifications: Set pressures 15–160 PSI @ max 250°F (121°C). Inlet/outlet sizes 3/4"×3/4" through 2"×2-1/2". Registered in all Canadian provinces and territories, CRN #0G8547.5C. Minimum recommended operating margin: 10 PSI or 25% of set pressure (whichever is greater) between system operating pressure and valve set pressure. Capacities from ~535,000 BTU/hr (3/4"×3/4" at 30 PSI) to 19,435,000 BTU/hr (2"×2-1/2" at 125 PSI). Includes lift lever for manual testing — perform a try lever test per Conbraco IOM ES1325 maintenance schedule.

ASME Section IV · HV Stamp National Board Certified Hot Water Service Only 15–160 PSI 3/4"–2" Inlet ASTM B584 Bronze Max 250°F (121°C) CRN #0G8547.5C 100% Factory Tested

Series 12 & 13 Series 12 & 13 — Low Pressure Steam Safety Valves

Series 13 — ASME Section IV low pressure steam safety valves for small to medium low pressure steam heating and supply boilers. Steam service — not for hot water boiler service. Bronze body (ASTM B584). Flat seat with PTFE faced disc for positive seal. Raised seating area for extended service life. Positive drainage of condensate from seat area. Top guiding. Available in top outlet (13-101) and side outlet configurations.

Sizes 3/4"–1-1/2" NPT. Set pressures 5–15 PSI. National Board capacity certified at 15 PSI. Registered in all Canadian provinces and territories, CRN #0G8547.5C. On your site: 13-211-B15 (3/4" x 3/4", 15 PSI, 475 lb/hr), 13-214-B15 (1-1/2" x 2", 15 PSI, 1,900 lb/hr).

Series 12-200 — ASME Section IV steam safety valves for medium and large commercial and industrial steam heating and processing boilers. Cast bronze, full nozzle design. PTFE faced elastomer soft seating for reduced seat sticking. All bronze construction, PTFE-coated O-ring seal, 3/8" NPT drain connection, rust-proofed steel spring. Sizes 2", 2-1/2", 3". Set pressures 5–15 PSI. On your site: 12-205-08 (2" x 2", 15 PSI, 2,500 lb/hr).

ASME Section IV · Steam Only 5–15 PSI Set Pressure Series 13: 3/4"–1-1/2" Series 12: 2"–3" ASTM B584 Bronze · PTFE Seat CRN #0G8547.5C

Series 19 Series 19 — Industrial Safety Relief Valves (ASME Section I & VIII)

The Conbraco Series 19 are full-nozzle industrial safety and relief valves for power boilers, unfired pressure vessels, and industrial process equipment. ASME Section I ("V" stamp — power boilers) and Section VIII ("UV" stamp — unfired pressure vessels and pressure piping). National Board capacity certified. Bronze body. 100% factory tested at ASME-certified setting stations.

Set pressures 15–1,200 PSI. Available in steam, air/gas, and liquid service configurations. Full size range available — contact us for the full Series 19 catalog. On your site: 19-KDCA-75 (1/2"×3/4", 75 PSI, 505 lb/hr steam), 19-EFEL-45 (1"×1-1/4", 45 PSI, 604 lb/hr), 19-KEEA-15 (1"×1", 15 PSI, 310 lb/hr steam). Specify stainless steel wetted trim (model 19S) for steam settings above 250 PSI.

ASME Section I · V Stamp ASME Section VIII · UV Stamp 15–1,200 PSI Steam · Air/Gas · Liquid Bronze Body 100% Factory Tested

Gauges · Ball Valves · Accessories Series 20/24/25 Gauges · Series 26 Gauge Cocks · Apollo Ball Valves

Liquid Level Gauges (Series 20, 24, 25): Bronze boiler water gauges with automatic ball checks — allows safe gauge glass replacement without shutting down the boiler. Series 20: rough bronze, standard glass (5/8" OD), EPDM seal, Teflon stem packing, 200 PSI @ 400°F / 400 PSI @ 100°F. Series 24: rough bronze, high-pressure glass, PTFE with Hypalon seals, 250 PSI @ 400°F / 500 PSI @ 100°F. Series 25: polished bronze, chain-lever operation, 3/4" NPT, 16" glass, 250 PSI @ 400°F / 500 PSI @ 100°F.

Series 26 Compression Gauge Cocks: Polished brass, soft metal seat and stuffing box, composite plastic wheel, 250 PSI @ 400°F. Used to isolate pressure gauges in steam and hot water service.

Apollo Ball Valves (70 Series, 76, 77CLF, 82LF): Conbraco introduced the Apollo 70 Series ball valve in 1968 — more than 150 million units sold. Standard bronze valves: 600 PSI CWP, 150 SWP. 76/96 stainless steel: 1/4"–1" = 2,000 PSI WOG; 1-1/4"–2" = 1,500 PSI WOG. 77CLF = lead free bronze, 600 PSI CWP. 82LF = 600# lead free stainless steel. All feature blow-out resistant stem; steel handle with hole for locking/tagging.

Series 38 Atmospheric Vacuum Breakers: Prevents backflow from siphoning in potable water systems.

Auto Ball Check Gauges Series 20: 200 PSI @ 400°F Series 24: 250 PSI @ 400°F HP Apollo 70 Series since 1968 77CLF = Lead Free Bronze 82LF = 600# Lead Free SS

How to read a Conbraco 10-600 Series part number

Format: 10-6[size code]-[PSI suffix] · Example: 10-617-09 = 1-1/2"×2" inlet/outlet, 45 PSI

10-6__-__	All Series 10-600 valves start with `10-6`
Size code (digits 5–6)	`04`=3/4"×3/4", `14`=3/4"×1", `05`=1"×1", `15`=1"×1-1/4", `06`=1-1/4"×1-1/4", `16`=1-1/4"×1-1/2", `07`=1-1/2"×1-1/2", `17`=1-1/2"×2", `08`=2"×2", `18`=2"×2-1/2"
PSI suffix (last 2 digits)	`01`=15 PSI, `05`=30, `07`=40, `09`=45, `10`=50, `12`=60, `15`=75, `20`=100, `25`=125, `34`=150, `36`=160

Source: Conbraco IOM document ES1325. Full pressure suffix table available at apollovalves.com. Call (901) 458-2000 for help decoding a part number.

Conbraco Relief Valve — Quick Selection Guide

Select by service type first (hot water vs. steam), then by set pressure. The valve set pressure must not exceed the boiler's MAWP. The valve BTU/hr (or lb/hr steam) capacity must equal or exceed the boiler's input rating. Call (901) 458-2000 for sizing help.

Series	Service	ASME Code / Stamp	Set Pressure	Sizes	Application	Shop
10-600	Hot Water only	Section IV · HV stamp	15–160 PSI	3/4"–2"	Commercial & industrial hot water heating boilers	10-615-07
13	Steam only	Section IV · HV stamp	5–15 PSI	3/4"–1-1/2"	Small–medium low pressure steam heating boilers	13-211-B15
12-200	Steam only	Section IV · HV stamp	5–15 PSI	2"–3"	Medium–large commercial & industrial steam heating boilers	12-205-08
19	Steam · Air/Gas · Liquid	Section I · V stamp Section VIII · UV stamp	15–1,200 PSI	1/4"–6"	Power boilers, pressure vessels, industrial process	19-KDCA-75
511G	Liquid/Air/Gas	Section VIII · UV stamp	Application-specific	1-1/4" (G orifice)	Unfired pressure vessels, industrial relief	511GFBK

⚠ Never reuse a relief valve that has discharged. After any discharge event, the seating surfaces may be damaged. Replace the valve — do not return it to service. Call (901) 458-2000 to source the correct replacement.

Commonly Ordered Conbraco Products

Browse all 2,574 →

10-615-07Hot water · 1"×1-1/4" · 40 PSI 10-615-15Hot water · 1"×1-1/4" · 75 PSI · 3,200k BTU 10-606-25Hot water · 1-1/4"×1-1/4" · 125 PSI · 7,390k BTU 10-617-09Hot water · 1-1/2"×2" · 45 PSI · 4,974k BTU 10-618-25Hot water · 2"×2-1/2" · 125 PSI · 19,435k BTU 13-211-B15Steam · 3/4"×3/4" · 15 PSI · 475 lb/hr 13-214-B15Steam · 1-1/2"×2" · 15 PSI · 1,900 lb/hr 12-205-08Steam · 2"×2" · 15 PSI · 2,500 lb/hr 19-KDCA-75Industrial · 1/2"×3/4" · 75 PSI · 505 lb/hr 19-EFEL-45Industrial · 1"×1-1/4" · 45 PSI · 604 lb/hr 19-KEEA-15Industrial · 1"×1" · 15 PSI · 310 lb/hr steam 511GFBKMAA0200Sect. VIII · G orifice · 1-1/4" · 200 PSI 20-350-00HP water gauge · 1/2" NPT · 12" HP glass 20-250-00Water gauge · 1/2" NPT · 12" standard glass 20-250-03Water gauge · 1/2" NPT · shorter glass 24-350-00HP gauge · 1/2" NPT · 12" HP glass · 500 PSI 24-350-03HP gauge · 1/2" NPT · ASME rated · 500 PSI 25-602-00Chain gauge · 3/4" · 16" glass · 500 PSI 26-305-28Gauge cock · 1/2" · polished brass · 250 PSI 9858R-72Gauge glass · 5/8"×72" standard 76-103-27ABall valve · 1/2" · SS · lockable 77CLF-106-27ABall valve · 1-1/4" · lead free bronze 82LF10301Ball valve · 1/2" · 600# lead free SS 38-103-01Atmospheric vacuum breaker · 1/2" NPT All Conbraco →Browse all 2,574 products

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SKU: 20-207-00

Conbraco 20-207-00 Gauge Glass Kit 3/4" x 16" Aluminum

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SKU: 18C-512-5-150

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SKU: 4V-500-03

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SKU: 10-605-25

Conbraco 10-605-25 1" FNPT x 1" FNPT Hot Water Relief Valve, 125 PSI, 4,272,000 BTU/hr

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SKU: 19-MEEA-90

Conbraco 19-MEEA-90 1" x 1" 90 PSI Steam Relief Valve

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SKU: 76F-104-27A

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SKU: 18C-512-5-125

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Need help selecting a Conbraco relief valve?

Tell us: hot water or steam boiler? BTU input (or lb/hr steam)? Inlet size? MAWP from the boiler nameplate? We'll find the right valve.

Get Valve Selection Help Call (901) 458-2000

Need Conbraco ball valves, backflow preventers, or butterfly valves?

Conbraco's Apollo Valves catalog is one of the broadest in the industry — beyond relief valves and gauges, it includes Apollo ball valves (70 Series, 2,000 PSI rated stainless, lead free bronze), butterfly valves, backflow prevention devices (Defender series), water pressure regulators, strainers, and actuators. If you need a Conbraco Apollo product not currently listed, call us — we can source from the full Conbraco line for commercial and industrial applications.

Inquire About Conbraco Products →

Conbraco / Apollo Valves — Frequently Asked Questions

Common questions on selecting, sizing, and applying Conbraco relief valves for boiler and pressure vessel service. Contact us or call (901) 458-2000 — we've been helping customers spec valves since 1967.

What is the difference between Series 10, 12/13, and 19 relief valves?

Series 10-600: Hot water boiler safety relief valves — ASME Section IV (HV stamp), 15–160 PSI, hot water service only. National Board certified at all pressure settings. Series 13 (3/4"–1-1/2") and Series 12-200 (2"–3"): Low pressure steam safety valves — ASME Section IV (HV stamp), 5–15 PSI, steam service only. Do not cross-apply hot water and steam valves — it is a code violation and safety hazard. Series 19: Industrial full-nozzle valves — ASME Section I (V stamp, power boilers) and Section VIII (UV stamp, unfired pressure vessels), 15–1,200 PSI, steam/air/gas/liquid. Call (901) 458-2000 with your boiler nameplate data to confirm the correct series.

How do I size a Conbraco hot water boiler relief valve?

Two requirements must both be met. 1. Set pressure ≤ MAWP: The valve set pressure must not exceed the boiler's maximum allowable working pressure (MAWP) stamped on the boiler nameplate. 2. BTU capacity ≥ BTU input: The valve's National Board certified BTU/hr capacity must equal or exceed the boiler's BTU input rating. Also: maintain a minimum operating pressure margin of 10 PSI or 25% of set pressure (whichever is greater) between the system's normal operating pressure and the valve set pressure — insufficient margin causes the valve to simmer, damaging the seat. Example: boiler rated 30 PSI MAWP, 2,000,000 BTU input → use a 30 PSI valve with ≥2,000,000 BTU capacity. Call (901) 458-2000 with your boiler model, BTU input, MAWP, and normal operating pressure.

Can a Series 10 hot water valve be used on a steam boiler?

No — this is a code violation and safety hazard. Conbraco Series 10-600 is certified for hot water heating service only. Steam service requires a pop-action safety valve specifically designed and certified for steam — the seat geometry, materials, and discharge characteristics are different. For low pressure steam heating boilers (5–15 PSI), use Series 13 (3/4"–1-1/2") or Series 12-200 (2"–3"). For power boilers or pressure vessels, use Series 19 (ASME Section I or VIII).

What does National Board capacity certified mean?

The BTU/hr (or lb/hr steam) capacity on the nameplate was independently tested by the National Board of Boiler and Pressure Vessel Inspectors — not just factory-calculated. National Board ratings are certified at 90% of actual capacity at 10% overpressure, per ASME methodology. All Conbraco safety and relief valves are 100% factory tested at ASME-certified setting stations. The HV stamp confirms ASME Section IV compliance for heating boilers. The NB symbol confirms National Board capacity certification. The CRN #0G8547.5C on the nameplate confirms registration in all Canadian provinces and territories per CSA B51.

What are the installation requirements for a Series 10-600 relief valve?

Per Conbraco IOM ES1325: mount vertically upright, direct to the pressure vessel — no shutoff valve, check valve, or flow restriction between the relief valve and the vessel. Discharge piping must be: no smaller than the valve outlet, independently supported, pitched to drain, terminated freely to atmosphere with a plain (unthreaded) end. Do not cap or plug the discharge outlet. Maintain a minimum 10 PSI or 25% operating pressure margin below the set pressure. Use proper wrenches on wrench pads only — not pipe wrenches. For testing cadence and full maintenance procedures, follow Conbraco IOM ES1325 (available at apollovalves.com) or contact a licensed boiler inspector. Call (901) 458-2000 with installation questions.

Should I replace a relief valve that has discharged?

Yes. Any relief valve that has opened under pressure should be replaced — not returned to service. High-velocity discharge flow can damage the seat and disc surfaces. A valve that re-closes after discharging may leak continuously or fail to open at the correct set pressure next time. Code and manufacturer guidance is clear: replace the valve after any discharge event. Call (901) 458-2000 with your existing Conbraco part number and we'll source the correct replacement.

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For emergencies, outside of business hours, call #901-604-7069