Kunkle Valve · An Emerson Brand · Patented 1875 · Fort Wayne, Indiana · ASME National Board Certified

Kunkle Valve (Emerson) -
ASME Safety and Relief Valves for Steam, Air, Gas & Liquid

Memphis Control Center stocks Kunkle Valve safety and relief valves for steam, air, gas, and liquid service on commercial and industrial boilers and pressure vessels. Series 6010 - the most widely specified Kunkle valve - ASME Section I and VIII, steam/air/gas, bronze body, 1/2" to 2-1/2", side outlet, full nozzle. Series 6021 - same with Teflon (PFA) disc insert for superior steam leak-off. Series 6030 - same with stainless steel trim. Series 6182 - top outlet version. Series 6252 - cast iron body, flanged, 1-1/2" to 6", ASME Section I/VIII. Model 0537 - ASME Section IV, low-pressure steam and hot water boiler relief valves. Model 0930 - cast iron, ASME Section IV, low-pressure steam. All Kunkle valves are National Board certified and set and tested at the factory per API 527. Family-owned, serving Memphis since 1967.

Browse All Kunkle Valve Products Call (901) 458-2000
Kunkle Valve · An Emerson Brand · Patented 1875 ASME Section I · Section IV · Section VIII National Board Certified Steam · Air · Gas · Liquid Service Family-Owned Since 1967
ASME Stamped · National Board CertifiedEvery Kunkle valve is ASME code stamped (V, HV, or UV stamp) and certified by the National Board of Boiler and Pressure Vessel Inspectors - required by most state and local boiler codes
Factory Set and TestedAll Kunkle valves are set, tested, and retested at the factory per API 527 seat tightness standards, then sealed to prevent field tampering with the set pressure
Section I · Section IV · Section VIIIKunkle covers all three ASME code sections: Section I (power boilers), Section IV (hot water and low-pressure steam heating boilers), and Section VIII (unfired pressure vessels)
Same-Day ShippingKunkle relief valves ship same day from Memphis, TN - free. Call (901) 458-2000 with your set pressure, pipe size, ASME section, and service (steam/air/water) and we will identify the correct valve
Kunkle Valve - the safety valve that started on a locomotive. In the mid-1870s, Erastus B. Kunkle, a machinist working on locomotives for the Pennsylvania Railroad in Fort Wayne, Indiana, faced a critical problem: overpressure in steam locomotive engines was causing dangerous failures. Kunkle invented the first lock-up pop safety valve - a spring-loaded valve that would automatically open when pressure exceeded a set limit, releasing steam safely, then snap closed again (the "pop" action). In 1875 Kunkle patented the invention, and the following year he and his brother-in-law entered the valve manufacturing business. The company was established in 1875/1876. What began as a solution for railroad locomotives became the standard for industrial safety valves across steam boilers, pressure vessels, and process equipment worldwide. Kunkle Valve is now an Emerson brand, part of Emerson's automation solutions portfolio, and continues to manufacture safety and relief valves to ASME Sections I, IV, and VIII with National Board certification. Kunkle valves are stocked as original equipment by boiler manufacturers and are the valve most commonly specified for boiler room replacements.

ASME Code Section Guide - Which Kunkle Valve Do You Need?

The most common selection question for Kunkle relief valves is which ASME section applies to your equipment. The section determines which Kunkle model series is correct. Call (901) 458-2000 with your boiler or vessel nameplate information and we will confirm the correct valve.

ASME SectionASME StampEquipment TypeTypical Set PressureKunkle Series at MCC
Section I V stamp Power boilers - fired pressure vessels (high-pressure steam boilers above 15 PSIG) Above 15 PSIG 6010, 6021, 6030, 6182, 6252
Section IV HV stamp Heating boilers - hot water heating boilers and low-pressure steam heating boilers (steam at or below 15 PSIG) 15 PSIG (steam) · 30–160 PSIG (hot water) 0537, 0930
Section VIII UV stamp Unfired pressure vessels - air receivers, heat exchangers, storage tanks, any pressure vessel that is not a boiler Varies by vessel design 6010 (K/L suffix), 6252

ASME Section I, IV, and VIII stamps are confirmed from the National Board of Boiler and Pressure Vessel Inspectors and Kunkle Technical Reference VCTDS-00398-EN (Emerson). The correct section is determined by the equipment type - always match to the equipment's nameplate ASME designation, not just the pressure.

Kunkle Valve Series at Memphis Control Center

The Kunkle series stocked at Memphis Control Center cover commercial and industrial steam, air, and hot water service across ASME Sections I, IV, and VIII. Contact us or call (901) 458-2000 with your set pressure, inlet size, service (steam/air/water), and ASME section needed.

Series 6010 Steam / Air / Gas - ASME Sec I & VIII - Bronze - Side Outlet

The Kunkle Series 6010 is the most widely specified Kunkle safety valve for commercial and industrial steam and air/gas service. Bronze body, brass trim, full nozzle design, side outlet. The full nozzle design gives optimum flow performance; the wide hex on the valve nozzle allows easy installation with a wrench. Available with optional O-ring seats for superior leak-free performance. Dual control rings allow precise adjustment of opening pressure (warn ring) and blowdown (blowdown ring). ASME Section I (steam, V stamp) and ASME Section VIII (air/gas and steam, UV stamp) - the service is encoded in the model number suffix after the dash (A = ASME Sec I steam, K = ASME Sec VIII air/gas, L = ASME Sec VIII steam, M = ASME Sec I/VIII steam). Set pressure and capacity stamped on nameplate.

ModelSizeSet PSIServiceShop
6010 Series - from your inventory
6010DCM01-AM01501/2" x 3/4"150Steam · Sec IShop
6010EDM01-LM00453/4" x 1"45Steam · Sec VIIIShop
6010EDM01-AM01253/4" x 1"125Steam · Sec IShop
6010EDM01-AM01753/4" x 1"175Steam · Sec IShop
6010FEM01-AM00151" x 1-1/4"15Steam · Sec IShop
6010FEM01-AM01501" x 1-1/4"150Steam · Sec IShop
6010GFE01-KM01501-1/4" x 1-1/2"150Air/Gas · Sec VIIIShop
6010GFM01-AM00151-1/4" x 1-1/2"15Steam · Sec IShop
6010GFM01-AM01751-1/4" x 1-1/2"175Steam · Sec IShop
6010GFM01AAM01501-1/4" x 1-1/2"150Steam · Sec IShop
6010HGM01AKM01501-1/2" x 2"150Air · Sec VIIIShop
6010HGM01-ALM00601-1/2" x 2"60Steam · Sec VIIIShop
6010HHM01-AM01502" x 2"150Steam · Sec IShop
6010HHM01AAM00402" x 2"40Steam · Sec IShop
6010JHM01-AM00302" x 2-1/2"30Steam · Sec IShop
6010JHM01-AM01252" x 2-1/2"125Steam · Sec IShop
6010JHM01-AM01752" x 2-1/2"175Steam · Sec IShop
6010JHM01-AM02502" x 2-1/2"250Steam · Sec IShop
6021JHT01-AM01702" x 2-1/2"170Steam · Sec I (Teflon disc)Shop
Bronze Body · Brass Trim ASME Sec I (V stamp) · Sec VIII (UV stamp) Steam · Air · Gas 1/2" to 2-1/2" Inlet 3 to 250 PSIG Full Nozzle · Side Outlet National Board Certified
Model 0537 & 0930 ASME Section IV - Low-Pressure Steam & Hot Water Boiler Relief Valves

The Kunkle Model 0537 is a bronze and cast iron relief valve specifically for ASME Section IV - hot water heating boilers and low-pressure steam heating boilers. The HV stamp (Section IV) is required on residential and commercial heating boiler pressure relief valves. The 0537 carries both the steam (HV) rating for low-pressure steam heating boilers at 15 PSIG and the hot water (HV) rating for hot water heating boilers. Bronze body, B584 alloy seat, stainless steel spring. Heavy-duty lift lever standard. The Model 0930 is a cast iron body, Section IV, low-pressure steam relief valve for larger-capacity heating boiler applications. Both are National Board certified with HV stamp.

ModelSizeSet PSIServiceShop
Model 0537 - ASME Section IV (HV Stamp)
0537-E01HM01251" x 1-1/4"125Water boiler · Sec IVShop
0537-E01-HM01501" x 1-1/4"150Water boiler · Sec IVShop
0537-G01-HM00301-1/2" x 2"30Steam boiler · Sec IVShop
0537G01-HM00601-1/2" x 2"60Steam/water · Sec IVShop
537-D01-AHM00753/4"75Steam/water · Sec IVShop
Model 0930 - ASME Section IV (HV Stamp)
0930H01-GC00152" x 2"15Steam boiler · Sec IVShop
0930J01-GC00152-1/2" x 2-1/2"15Steam boiler · Sec IVShop

Section IV note: Steam heating boilers at or below 15 PSIG and hot water heating boilers (any pressure) require ASME Section IV (HV stamp) relief valves, not Section I (V stamp) or Section VIII (UV stamp). Using the wrong ASME section is a code violation. Call (901) 458-2000 if unsure which section applies to your boiler.

ASME Section IV (HV Stamp) Hot Water Heating Boilers Low-Pressure Steam Heating Boilers Bronze · Cast Iron National Board Certified
Series 6252 & 6283 Cast Iron / Flanged - Large Capacity Steam & Gas - ASME Sec I & VIII

The Kunkle Series 6252 is a cast iron body, stainless steel trim safety valve for larger-capacity steam, air, and gas applications requiring flanged connections. Available in 1-1/2" through 6" flanged inlet, ASME Section I (V stamp) and Section VIII (UV stamp), set pressures 10 to 250 PSIG, temperature range -20°F to 406°F. Used on industrial steam boilers, steam headers, and pressure vessels where high-capacity relief is required and flanged connections are specified. The Series 6283 is a bronze body, over-sized side outlet version of the 6010 series for applications requiring extra discharge capacity.

ModelSizeSet PSIServiceShop
Series 6252 - Flanged, Cast Iron
6252ALJ01-LS2-1/2" x 4"100Steam · Sec I · FlangedShop
6252FLJ01-LS2-1/2" x 4"100Female x Female · FlangedShop
Series 6283 - Oversized Side Outlet, Bronze
6283HGM01-AM00151-1/2" x 2-1/2"15Steam · Sec IShop
Cast Iron Body (6252) SS Trim (6252) Flanged Connections 1-1/2" to 6" (6252) ASME Sec I · Sec VIII 10 to 250 PSIG
Other Kunkle Models Model 19 (Adjustable Liquid) · Model 20 (Non-Code) · Full Kunkle Line Available

Memphis Control Center also stocks Kunkle Model 19 adjustable liquid relief valves (flanged, adjustable set pressure range, for liquid service) and Model 20 non-code relief valves. The full Kunkle product line ranges from 1/4" NPT to 6" flanged, set pressures from vacuum to very high pressure, service temperatures from cryogenic to elevated temperatures, and materials including brass, bronze, carbon steel, stainless steel, cast iron, and aluminum. If you need a Kunkle model not listed here, call (901) 458-2000 and we will confirm availability and lead time.

ModelDescriptionShop
19-EO3-MG1" x 1" · 150# flanged · adjustable liquid relief · 135–154 PSI rangeShop
20-H01-MG 100PSINon-code relief valve · set at 100 PSIShop

Kunkle full product range (not all stocked - call to order): Series 6010, 6021, 6030, 6121, 6130, 6182, 6186, 6221, 6230, 6252, 6254, 6283, 6933, 6934, 6935 (bronze, ASME Sec I/IV/VIII) · Series 300, 600, 900, 910, 911, 916, 917, 920, 921, 927 (carbon steel / stainless, higher pressures) · Model 0537, 0930 (Sec IV heating boilers) · Models 1, 2 (brass, ASME Sec VIII air/gas) · Models 541, 542, 548 (brass, air and gas, Sec VIII) · Models 189, 363 (cryogenic service) · Model 30 (non-code air/gas)

Adjustable Liquid Relief Non-Code Options 1/4" NPT to 6" Flanged Vacuum to High Pressure Cryogenic to High-Temp Service

Most-Ordered Kunkle Valves

Browse all Kunkle products →
6010JHM01-AM01252"x2-1/2" · 125 PSI · steam · Sec I 6010JHM01-AM01752"x2-1/2" · 175 PSI · steam · Sec I 6010JHM01-AM02502"x2-1/2" · 250 PSI · steam · Sec I 6010JHM01-AM00302"x2-1/2" · 30 PSI · steam · Sec I 6021JHT01-AM01702"x2-1/2" · 170 PSI · Teflon disc 6010HHM01-AM01502"x2" · 150 PSI · steam · Sec I 6010HGM01AKM01501-1/2"x2" · 150 PSI · air · Sec VIII 6010EDM01-AM01753/4"x1" · 175 PSI · steam · Sec I 6010EDM01-AM01253/4"x1" · 125 PSI · steam · Sec I 6010EDM01-LM00453/4"x1" · 45 PSI · steam · Sec VIII 6010GFE01-KM01501-1/4"x1-1/2" · 150 PSI · air · Sec VIII 0537-E01-HM01501"x1-1/4" · 150 PSI · water boiler · Sec IV 0537-E01HM01251"x1-1/4" · 125 PSI · water boiler · Sec IV 0537-G01-HM00301-1/2"x2" · 30 PSI · steam boiler · Sec IV 537-D01-AHM00753/4" · 75 PSI · Sec IV 0930J01-GC00152-1/2"x2-1/2" · 15 PSI · steam · Sec IV 6252ALJ01-LS2-1/2"x4" · 100 PSI · flanged · Sec I 6252FLJ01-LS2-1/2"x4" · 100 PSI · flanged All Kunkle →Browse all Kunkle Valve products
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Frequently Asked Questions — Kunkle Safety Relief Valves

Common questions from boiler technicians, mechanical engineers, and facility managers about Kunkle ASME safety and relief valves. Contact us or call (901) 458-2000 with your set pressure, pipe size, and ASME section.

What is the difference between ASME Section I, Section IV, and Section VIII for relief valves?

Section I (V stamp): power boilers — fired pressure vessels, typically high-pressure steam boilers above 15 PSIG. Kunkle 6010, 6021, 6030, 6182, and 6252 are available with Section I. Section IV (HV stamp): heating boilers — hot water heating boilers (any pressure) and low-pressure steam heating boilers at or below 15 PSIG. Kunkle 0537 and 0930 are Section IV. Section VIII (UV stamp): unfired pressure vessels — air receivers, heat exchangers, storage tanks, any pressure vessel that is not a boiler. Kunkle 6010 models with K (air/gas) or L (steam) service suffixes are Section VIII. The correct section is determined by the equipment type — always match to the equipment nameplate. Using the wrong section is a code violation.

How do I read a Kunkle 6010 model number?

For the 6010 series: the first four digits (6010) are the series. The orifice letter (D, E, F, G, H, J) follows — larger letters = larger orifice area and greater flow capacity. Then the outlet connection letter. Then M01 (standard trim). Then the service suffix after the dash: A = Section I steam; K = Section VIII air/gas; L = Section VIII steam; M = Section I and VIII steam. Then the set pressure: AM0150 = 150 PSI set. Example: 6010JHM01-AM0150 = Series 6010, J orifice (large), H outlet, M01 trim, Section I steam, 150 PSI set. Source: Kunkle Technical Reference VCTDS-00398-EN and Valves Depot nameplate decoder.

What does the Teflon disc insert in the 6021 series do?

The 6021 series is identical to the 6010 except for a Teflon (PFA) disc insert on the valve seat. The Teflon insert provides superior leak-free shutoff after opening, compensating for minor surface imperfections and providing a more positive bubble-tight seal on return. Specified for steam service only — the Teflon insert is not suitable for air/gas service at elevated temperatures. Common on high-pressure steam boilers where tight shutoff after popping is critical.

Why does a Kunkle relief valve need to be National Board certified?

The National Board of Boiler and Pressure Vessel Inspectors independently verifies that a manufacturer meets ASME Code requirements and that the valve's rated relieving capacity has been tested. This certification is required by most state boiler codes and jurisdictions as a condition of boiler or pressure vessel operation. A valve without National Board certification cannot legally serve as the ASME-required overpressure protection on a boiler or pressure vessel in most US jurisdictions. All Kunkle valves at Memphis Control Center carry National Board certification.

Can I adjust the set pressure on a Kunkle valve in the field?

No. Kunkle valves are set, tested, and sealed at the factory per API 527 standards. Adjusting the set pressure in the field voids the ASME stamp and National Board certification — a code violation. If a valve is opening at the wrong pressure, either the wrong valve was installed, the valve has failed, or the system pressure has changed. Order the correct set pressure from Memphis Control Center. Call (901) 458-2000 with your required set pressure, inlet size, ASME section, and service.

What is the difference between the Kunkle 0537 and the 6010 for steam boilers?

The 0537 is for ASME Section IV — heating boilers: hot water heating boilers and low-pressure steam heating boilers at or below 15 PSIG. HV stamp. The 6010 is for ASME Section I (power boilers, V stamp) and/or Section VIII (unfired pressure vessels, UV stamp). If your boiler is a commercial heating boiler or residential hot water boiler, you need the 0537. If your boiler is an industrial or high-pressure steam boiler above 15 PSIG, you need the 6010 with an A or M service suffix. Using the wrong section is a code violation. Call (901) 458-2000 with your boiler nameplate information and we will confirm the correct valve.

Need a Kunkle Relief Valve?

Call us with your set pressure, inlet pipe size, service (steam / air / water), and ASME section (I, IV, or VIII). Same-day shipping on stocked valves from Memphis, TN.

Call (901) 458-2000 Browse All Kunkle Products Contact Us

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