Kunkle relief valves are spring-loaded safety valves used to protect steam boilers, air compressors, pressure vessels, and liquid systems from overpressure. The brand has built industrial valves for almost 150 years.
Reviews are thin, because these valves sell through distributors. This means the best evidence is supplier specs, ASME certification details, and published prices from $297 to $618.
So what does that mean for you? Our team at Optimal Weight Plan dug into the models, certifications, and costs. Here's the full breakdown before you buy.
What Are Kunkle Relief Valves?
Kunkle relief valves are spring-loaded safety devices that open automatically to release excess pressure from steam, air, gas, and liquid systems. The Kunkle name has been attached to industrial valves for almost 150 years, according to supplier Valves Depot.
Many boilers and air compressors ship from the factory with a Kunkle valve already installed. When one needs replacing, buyers order by the model number printed on the original data tag.
This is an industrial product, not a consumer gadget. Our team at Optimal Weight Plan reviewed it the same way we review everything else: by checking what the maker claims, what suppliers publish, and what buyers actually report.
Quick Facts:
| Detail | Value |
|---|---|
| Product type | Safety and pressure relief valves |
| Brand history | Almost 150 years |
| Typical services | Steam, air/gas, and liquid |
| Common materials | Bronze and stainless steel |
| Price range seen | $297-$618 |
What Features Do Kunkle Valves Have?
Kunkle valves come in several body and trim configurations built for different service conditions. Bronze bodies with threaded inlets are common on general steam and air models, while stainless steel versions suit liquid and corrosive service.
Some models use an angle lapped seat for tight shut-off. Others offer resilient or O-ring seats when low leakage matters most.
The Kunkle 140-B01 shows how specific the range gets. It is a 3/8 inch stainless steel liquid relief valve with a 3/8 inch MNPT inlet and a 1/2 inch FNPT side outlet.
How Do Kunkle Relief Valves Work?
A Kunkle relief valve stays closed under spring force until system pressure reaches its set pressure, then it lifts to discharge fluid. Once pressure falls back, the spring reseats the valve and the system returns to normal.
Set pressure matters. A setting that is too low causes premature lifting, while one that is too high weakens overpressure protection.
Capacity matters just as much. Steam capacity is measured in pounds per hour (lb/hr), air and gas in SCFM, and liquid in gallons per minute (GPM) or liters per minute (3.8 L per gallon).
How Do You Size a Kunkle Valve?
Sizing starts with the worst credible overpressure event, not the pipe size. Examples include equipment failure, a blocked outlet, or external fire exposure.
The calculated relieving capacity then has to be met or exceeded by the valve's certified capacity. Critical applications call for an engineering review.
Steps to Select a Kunkle Valve:
- Identify the medium: steam, air/gas, or liquid
- Confirm the equipment's maximum allowable working pressure (MAWP)
- Set the required set pressure with a margin above normal operation
- Calculate the required relieving capacity
- Check the applicable ASME code section and certification
- Review back pressure, materials, and connections
What Are the Benefits of Kunkle Relief Valves?
The main benefit is dependable overpressure protection backed by a long manufacturing history. Dante Valve describes the brand's reputation for quality as one that still stands against competing relief valves.
Wide model coverage is the second benefit. Valves Depot lists 218 Kunkle results, so most boilers, compressors, and pressure vessels have a matching option.
Do Kunkle Valves Cover Steam, Air, and Liquid Service?
Yes, Kunkle valves cover all three service types, but each model is rated for specific conditions. A valve suited to steam should not be used on a liquid system without checking its ratings.
Common Kunkle Models by Application:
| Application | Example Models |
|---|---|
| Steam generators | 6121 and 6221 |
| Air compressors | 912, 913, 918, 919 |
| Pressure vessels | 912, 913, 918, 919 |
| Liquid systems | Liquid relief models such as 140 |
What Do Kunkle Relief Valve Reviews Say?
Verified buyer reviews are scarce, because most Kunkle valves sell through industrial distributors rather than consumer review platforms. Breathing Air Systems and Control Specialties both show no reviews on the Kunkle listings we checked.
Here is the honest takeaway. The strongest signals come from supplier feedback and the brand's track record, not from star ratings on individual valves.
What Do Buyers Like About Kunkle Valves?
Buyers praise fast shipping, fair prices, and good communication on used and surplus listings. One eBay seller shows 4.9 out of 5 stars for shipping cost and communication, and another buyer called the item and price good.
Those ratings describe the sellers, not the valve itself. Still, they show active resale demand for the brand.
What Are the Common Complaints?
The main complaint is availability and cost rather than performance. Control Specialties notes that product shipping is subject to factory availability, and prices reach $618 for a stainless liquid relief valve.
Wrong model choice is the other risk. Supplier guidance warns against selecting by connection size alone.
How Do Kunkle Valves Compare With Apollo Valves?
Kunkle and Apollo both make safety relief valves for steam, air, and liquid, so the right choice depends on the exact application. Control Specialties publishes a dedicated guide comparing Apollo relief valves with Kunkle models.
Apollo Series 19 valves appear next to Kunkle in the same supplier catalogs. Valves Depot lists Kunkle 19-series models at $297-$531, which gives a useful price anchor.
Kunkle 19-Series Prices at Valves Depot:
| Model | Size | Price |
|---|---|---|
| 19-C01-MG | 0.5 x 0.75 inch | $298 |
| 19-D01-MG | 0.75 x 0.75 inch | $297 |
| 19-E01-MG | 1 x 1 inch | $345 |
| 19-F01-MG | 1.25 x 1.25 inch | $445 |
| 19-G01-MG | 1.5 x 1.5 inch | $531 |
What Are the Risks of Choosing the Wrong Kunkle Valve?
A mismatched valve can fail to protect equipment, leak, or lift too early. Common mistakes include using normal operating pressure as the only sizing input and ignoring the service medium.
Back pressure is easy to overlook. Back pressure raises set pressure one to one and cuts capacity, and the 140-B01 listing advises against back pressure above 10% of set pressure.
Who Should Not Install a Kunkle Valve Themselves?
Anyone without pressure system training should leave sizing, installation, and testing to a qualified professional. Boilers and pressure vessels can cause serious injury when protection fails.
Think of it this way: a relief valve is the last line of defense. Guessing is not an option.
Are Kunkle Relief Valves Certified and Safe?
Yes, many Kunkle models carry ASME certification, but the certification must match the equipment being protected. Certain models hold Section IV certification for defined applications and pressure settings.
ASME Section I covers power boilers, Section IV covers heating boilers, and Section VIII covers pressure vessels with V and UV marks. Certification under one section does not satisfy another.
ASME Sections at a Glance:
| Section | Applies To |
|---|---|
| Section I | Power boilers |
| Section IV | Heating boilers and low-pressure systems |
| Section VIII | Pressure vessels |
How Much Do Kunkle Relief Valves Cost?
Kunkle relief valves cost roughly $297 to $618 for the models we checked, with price rising by size and material. Small bronze 19-series valves start near $300, while the stainless 140-B01 sits at $618.
Are Kunkle Valves Worth the Price?
Yes, for most buyers the price is reasonable compared with the cost of equipment damage or downtime. The valve protects a boiler, compressor, or vessel worth far more.
The catch? Paying for the wrong model wastes the money. Verify certification, capacity, and ratings against current manufacturer specifications before ordering.
Where Can You Buy Kunkle Relief Valves?
Industrial valve distributors are the best place to buy Kunkle relief valves, with Control Specialties, Valves Depot, and Breathing Air Systems all stocking them. Amazon and eBay also list new and surplus units.
Order by the model number on the data tag. If the tag is missing, Valves Depot says its experts can help identify the right valve for the application.
Steps to Buy a Kunkle Valve:
- Find the model number on the original data tag
- Confirm the service medium, set pressure, and capacity
- Check the ASME certification the equipment requires
- Compare prices across authorized distributors
- Confirm stock, since shipping can depend on factory availability
Why Should You Try Optimal Weight Plan?
Most of what we review is about health, not hardware. But the same rule applies: skip the guesswork and check the specs before you commit.
Our team at Optimal Weight Plan builds every review around real data and real user experiences, not marketing copy. That is the approach our coaches bring to your weight loss plan too.
Ready for a plan built around your body and your goals? Book a free call with our coaches and start with a routine that fits.
