Frequently Asked Questions

A safety valve is a pressure relief device that automatically opens at a preset pressure to protect equipment from overpressure. Safety valves are designed for compressible media like steam, air, and gas. They open rapidly (pop action) and are governed by ASME Section VIII or Section I codes.

A relief valve is a pressure relief device designed for liquid service. Unlike safety valves that pop open, relief valves open proportionally as pressure increases above the set point. They are commonly used in water heaters, hydraulic systems, and liquid process lines.

Safety valves are for compressible fluids (steam, air, gas) and open with a quick pop action. Relief valves are for incompressible fluids (water, oil) and open proportionally. Safety relief valves can handle both types of media.

Set pressure is the inlet pressure at which a safety valve begins to open under service conditions. It is the pressure at which the valve ‘pops’ to relieve excess pressure, and is typically stamped on the valve nameplate.

Blowdown is the difference between the set pressure (when the valve opens) and the reseating pressure (when the valve closes). It is expressed as a percentage of set pressure. Lower blowdown means the valve closes closer to set pressure.

Accumulation is the pressure increase above the maximum allowable working pressure (MAWP) during a relief event. ASME codes typically allow 3% accumulation for fired vessels and 10% for unfired vessels.

ASME certification means the valve has been designed, tested, and manufactured in accordance with ASME Boiler and Pressure Vessel Code standards. Certified valves carry the ASME UV or V stamp, indicating they meet strict performance requirements.

Safety valves handle compressible media including steam, air, natural gas, nitrogen, and other gases. Relief valves handle incompressible media such as water, thermal oil, and other liquids. Safety relief valves are rated for both.

Most jurisdictions and insurance companies require safety valve testing or replacement every 1-5 years depending on the application, media, and local codes. Boiler safety valves typically require annual testing. Always consult your local jurisdiction for specific requirements.

A National Board certified valve has been registered with the National Board of Boiler and Pressure Vessel Inspectors. This provides traceability, ensures the valve meets ASME code requirements, and is typically required for insurance and jurisdictional compliance.

Selecting the right safety valve requires knowing your system’s maximum allowable working pressure (MAWP), required relieving capacity, media type (steam, air, liquid), temperature, and inlet/outlet connection sizes. Use our Configure & Price tool for guided selection.

Orifice size determines the valve’s relieving capacity. Common ASME orifice designations range from D (0.110 in²) to T (26.0 in²). The required orifice depends on your flow rate, set pressure, and media type. Our product pages list the orifice size for each valve.

Common body materials include bronze (for steam/air up to 400°F), carbon steel (higher pressures/temperatures), and stainless steel (corrosive media). Trim materials, seats, and seals vary by application requirements.

Safety valves come in NPT (threaded), flanged (150#, 300# and higher), and weld-end connections. Select the connection that matches your piping system. NPT is most common for smaller valves; flanged for larger industrial applications.

Standard safety valves are designed for compressible media only. For liquid service, you need a relief valve or safety relief valve specifically rated for liquid. Using the wrong type can result in chatter, damage, or failure to protect.

Direct-acting valves use system pressure against a spring to open. Pilot-operated valves use a pilot to sense pressure and control the main valve. Pilot-operated valves offer tighter shutoff and are used in high-pressure or high-capacity applications.

We offer direct cross-references for Kunkle and Apollo safety valves. Search by your existing model number or use our Valve Finder Tool. Aquatrol valves provide equivalent ASME-certified performance with the same orifice, set pressure, and connection specifications.

Yes. Aquatrol manufactures ASME-certified safety valves that are direct replacements for most major brands. As long as the set pressure, orifice size, connection type, and media rating match, an Aquatrol valve can be used as a drop-in replacement.

Use our Valve Finder Tool or contact our sales team with your Kunkle model number. We maintain cross-reference data for Kunkle’s most popular models including the 6010, 6021, 6030, 6182, and 6283 series.

Provide your Apollo model number and we can identify the matching Aquatrol valve. Common Apollo replacements include their 10-600 and 10-400 series. Our Configure & Price tool can also help identify the right replacement.

Yes. Aquatrol valves carry ASME UV and V stamps and are National Board registered, just like the major brands they replace. All certifications are stamped on the nameplate.

To find the right replacement, provide: existing valve model number or nameplate data, set pressure (PSI), connection size and type, media type (steam, air, water, etc.), and temperature. Photos of the nameplate are also very helpful.

A new valve can be ordered at any set pressure within its range. However, the set pressure must not exceed the MAWP of the vessel or system. Always verify with your local inspector or engineer before changing set pressure.

Some valves can be rebuilt with new seats, springs, and seals. However, rebuilt valves must be retested and recertified to ASME standards. In many cases, ordering a new valve is more cost-effective and ensures full compliance.

Install the valve vertically (upright) directly on the vessel or as close to it as possible. Do not install valves in horizontal piping or with excessive pipe between the valve and vessel. Ensure inlet piping is at least the size of the valve inlet.

Most safety valves must be installed vertically with the spindle upright. Horizontal installation can cause improper seating, chatter, and premature failure. Check the manufacturer’s installation instructions for your specific valve model.

Regular maintenance includes visual inspection for corrosion or damage, testing the valve by lifting the test lever (if equipped), and verifying the valve reseats properly. Operating conditions and local codes determine the maintenance schedule.

Common causes include: set pressure too close to operating pressure (should be at least 10% above), oversized valve, excessive backpressure, dirt or debris on the seat, or damage to the seat or disc. Contact us for troubleshooting help.

A test lever (or lift lever) allows manual opening of the valve to verify it is not stuck. ASME and insurance companies often require periodic lever testing. Only test when the system is at 75% or more of set pressure to ensure proper reseating.

Built-up backpressure from discharge piping affects valve performance. Conventional valves can handle up to 10% backpressure. Balanced bellows valves handle higher backpressure. Excessive backpressure reduces capacity and can prevent proper opening.

You can order online through our website, email sales@safetycontrolvalves.com, or call (262) 320-7101. For custom configurations, use our Configure & Price tool to build your valve specification and request a quote.

We ship via UPS and freight carriers depending on order size. Standard shipping typically delivers within 3-5 business days. Expedited shipping is available for urgent needs. Contact us for shipping quotes on large orders.

Yes, we offer quantity discounts for larger orders. Contact our sales team at sales@safetycontrolvalves.com or call (262) 320-7101 for volume pricing on your specific valve requirements.

We accept returns of unused, undamaged valves within 30 days of purchase. Custom-configured valves and valves that have been installed or tested are not eligible for return. Contact us for a return authorization before shipping.

Yes. Use our Configure & Price tool for instant online quotes, or contact our sales team for custom quotes. We typically respond to quote requests within one business day.

ASME Section I covers boiler safety valves (V stamp). ASME Section VIII covers pressure vessel safety valves (UV stamp). Section IV covers heating boilers. Each section has specific requirements for capacity, testing, and certification.

The V stamp indicates a valve certified for ASME Section I (power boilers). The UV stamp indicates certification for ASME Section VIII (pressure vessels). Both require third-party testing and quality system audits.

Most jurisdictions and insurance companies require National Board registration for safety valves on boilers and pressure vessels. Registration provides traceability and verifies the valve meets ASME code requirements.

ASME certified valves include a nameplate stamped with the ASME symbol, set pressure, capacity, and model information. A Certificate of Compliance and National Board registration number are also provided.

Aquatrol is an American manufacturer of ASME-certified safety and relief valves based in the USA. They produce a full line of bronze, steel, and stainless steel valves for steam, air, gas, and liquid applications. Safety Control Valves is an authorized Aquatrol distributor.

We carry the full Aquatrol line including: Series 69/70 (bronze steam), Series 130/140/150 (bronze air/gas), Series 160/170 (bronze liquid), Series 530/540/550 (carbon steel), Series 560 (stainless steel), and Series 740/741/742/743 (safety relief valves).

Yes. Aquatrol manufactures their safety valves in the United States. All valves are ASME certified and National Board registered, with full traceability from raw materials to finished product.

Yes. Safety Control Valves is an authorized distributor for Aquatrol Valve Company. We carry their complete product line and can provide factory-direct pricing, technical support, and fast shipping.

For sanitary and hygienic applications, the Aquatrol 563 Series (bronze, tri-clamp connection) and 573 Series (stainless steel, tri-clamp) are purpose-built with tri-clamp end connections that meet 3-A sanitary standards. For higher pressures or specialized requirements, the 743 Series stainless steel valve can be paired with sanitary adapters. These valves are commonly used in pharmaceutical manufacturing, food & beverage processing, dairy, and biotech applications where clean-in-place (CIP) compatibility and product purity are critical. View sanitary valve options.

Yes. The Aquatrol 741 Series (cast iron body), 742 Series (cast steel), and 743 Series (stainless steel) are all available with flanged inlet connections from 1″ through 8″ in ANSI Class 150 through Class 1500. Flanged valves are ideal for large-diameter piping systems, high-pressure process vessels, and applications where threaded connections are impractical. We also supply bolt-on flange kits for adapting threaded valves. Explore flanged valve options or request a quote for custom configurations.

For corrosive media or environments, all-stainless steel construction is essential. The 743 Series offers full 316 stainless steel wetted parts for aggressive chemicals, acids, and caustic solutions. The 563 and 573 Series provide stainless steel options with tri-clamp connections for sanitary-corrosive crossover applications. For clean steam systems, stainless internals prevent contamination and resist the erosive effects of wet steam. Key considerations include media compatibility, temperature range, and whether FDA/3-A compliance is needed. See all-stainless options.

Cryogenic applications (down to -320°F / -196°C) require specially designed valves with materials rated for extreme cold. The Aquatrol 740 Series and 743 Series can be configured with cryogenic-rated trim and seats for LNG, liquid nitrogen, liquid oxygen, and industrial gas service. Critical features include spring materials that maintain performance at extreme temperatures and seat materials (PTFE or metal-to-metal) that seal reliably under thermal cycling. Learn about cryogenic valve options.

Yes. The Aquatrol 140 Series is rated up to 6,000 psig and is designed specifically for high-pressure air, gas, and hydraulic systems. The 740, 741, 742, and 743 Series also cover elevated pressure ranges depending on size and configuration. High-pressure applications—including compressor discharge, gas transmission, and hydraulic test systems—require careful valve selection based on set pressure, back pressure, and required capacity. Explore high-pressure options or contact our engineers for sizing assistance.

The Aquatrol 747 Series and 748 Series are specifically designed to meet NSF/ANSI 61 and NSF/ANSI 372 lead-free requirements for potable water systems. These valves comply with the U.S. Safe Drinking Water Act and are approved for domestic water heaters, potable water boilers, and municipal water systems. Lead-free certification is mandatory in most jurisdictions for any valve in contact with drinking water. View potable water valve options.

Selection depends on your application requirements:

• 69 Series — Bronze body, economical choice for steam, air, and non-corrosive gas/liquid up to 400 psig. Ideal for boilers, compressors, and general industrial use.
• 740 Series — Cast steel body, higher pressure ratings, suited for steam, air, gas, and petrochemical applications where steel construction is required by code or environment.
• 743 Series — 316 stainless steel, required for corrosive media, sanitary/pharmaceutical, cryogenic, or clean steam applications where contamination resistance is critical.

Use our Configure & Price tool to compare options side-by-side, or contact us for engineering guidance.

Yes. Because Aquatrol valves are built to order, nearly any combination of set pressure, body material, seat material, spring range, and end connection is available. Common custom requests include non-standard set pressures, special seat materials (Viton, EPDM, PTFE, metal-to-metal), extended bonnets for high-temperature or cryogenic service, and test certifications (ASME capacity certification, National Board testing, material traceability). Lead times are typically 10–14 business days. Submit an RFQ for custom configurations.