A28W-16T Safety Valve: The Complete Guide to All-Copper Threaded Full-Lift Safety Valves

Time：2026/4/8 19:33:45 Category：TECHNICAL ARTICLE Source： Click：

——Discover how Shanghai WUYUE Pump Valve Group Co., Ltd. delivers reliable, corrosion-resistant overpressure protection for water, air, and steam systems

When it comes to protecting small-to-medium pressure vessels, hot water heaters, air compressors, and steam equipment, the A28W-16T Safety Valve stands out as a premium choice. This all-copper, spring-loaded, full-lift (slightly open/unclosed) threaded safety valve combines excellent corrosion resistance with reliable performance at temperatures up to 200°C.

In this comprehensive guide, we’ll explore the A28W-16T’s features, applications, technical specifications, and why Shanghai WUYUE Pump Valve Group Co., Ltd. is a trusted manufacturer of copper alloy safety valves for global customers.

What is the A28W-16T Safety Valve?

The A28W-16T spring slightly open (full-lift) unclosed safety valve is a direct spring-loaded, threaded safety valve manufactured primarily from copper alloy (all-copper or internal copper construction). It belongs to the A28 series of full-lift safety valves, which are characterized by their open bonnet design, manual test lever, and maximum discharge capacity.

Key Features at a Glance:

The “T” in A28W-16T stands for copper (Tong in Chinese pinyin) , indicating the valve body and internal wetted parts are made from copper-based alloys, typically brass (CZ121/CW614N) or bronze.

Product Features and Functional Advantages

1. All-Copper Construction – Superior Corrosion Resistance

Unlike cast iron or carbon steel valves that rust over time, the A28W-16T’s copper alloy body provides:

• Excellent resistance to atmospheric corrosion – ideal for humid environments or outdoor installations.

• Compatibility with potable water systems – no rust contamination of drinking water.

• Long service life – copper naturally forms a protective patina, not destructive rust.

• Lightweight – easier to handle and install than steel valves.

2. Full-Lift (Full-Open) Design

The A28W-16T features a full-lift (also described as “slightly open” in some literature) characteristic:

• The valve disc lifts completely off the seat at set pressure.

• Provides maximum discharge capacity – typically 2-3x higher than micro-lift valves of the same size.

• Eliminates chatter – reduces seat wear and extends valve life.

• Ideal for compressible fluids (air, steam, gas) where rapid pressure reduction is needed.

3. Open Bonnet with Manual Test Lever

The open bonnet design with test lever offers practical advantages:

• Manual testing – operators can verify valve operation without system shutdown (critical for safety compliance).

• Visual inspection – operators can see the stem move when the valve opens.

• Easy field cleaning – debris or scale can be removed without full disassembly.

• Cost-effective – simpler construction than fully enclosed bellows valves.

4. Threaded Connections for Easy Installation

Available with standard male or female threads:

• G (BSP) – parallel threads per British standard.

• R (BSPT) – tapered threads for pressure-tight joints.

• NPT – American National Standard tapered threads.

• Custom threads – upon request.

Common sizes range from DN15 (1/2″) to DN50 (2″).

5. Wide Set Pressure Range

The A28W-16T can be factory-set to any pressure within the nominal pressure rating:

Set pressure tolerance: ±3% as standard, ±1% available upon request.

6. Manual Test Lever – A Critical Safety Feature

The A28W-16T includes a manual test lever (also called a lifting lever) that allows operators to:

• Verify freedom of movement – ensures the disc isn’t stuck to the seat.

• Perform routine testing – required by many safety codes (ASME, PED, Chinese boiler regulations).

• Manually relieve pressure – in emergency situations or during maintenance.

• Clean the seat – lifting the lever can dislodge small debris.

Important: The test lever should never be used to hold the valve open continuously. It is for momentary testing only.

7. Compliance with International Standards

While standard production follows GB/T 12243 (Chinese national standard for spring-loaded safety valves), Shanghai WUYUE can manufacture the A28W-16T to meet:

• American standards – ASME Section VIII, API 527

• Japanese standards – JIS B 8210

• German standards – DIN 3320

• Russian standards – GOST 12.2.085

• British standards – BS 1123

Applications of the A28W-16T Safety Valve

The A28W-16T’s copper construction, full-lift design, and manual test lever make it a popular choice in:

🔹 Air Compressors and Pneumatic Systems

• Installed on small-to-medium reciprocating air compressor tanks (50-1000 liters).

• Full-lift design provides rapid pressure relief when multiple compressors cycle.

• Manual lever allows weekly testing per safety regulations.

🔹 Hot Water Heaters and Boilers

• Protects domestic hot water tanks and small commercial boilers from thermal expansion overpressure.

• Copper body eliminates rust contamination of potable water.

• Test lever allows verification of valve operation during annual maintenance.

🔹 Steam Equipment

• Suitable for small steam generators, steam tables, autoclaves, and sterilizers up to 200°C.

• Full-lift design quickly vents large volumes of steam.

• Open bonnet allows visual confirmation of steam release.

🔹 Solar Thermal Systems

• Copper construction is compatible with glycol-based heat transfer fluids.

• Threaded connections simplify installation on solar collectors and storage tanks.

• Test lever allows field checking of valve operation.

🔹 Marine and Offshore

• Brass or bronze construction resists saltwater corrosion in engine room cooling systems and compressed air systems.

• Manual lever enables crew to test valves during routine safety drills.

🔹 Food and Beverage Processing

• Copper alloy valves are acceptable for non-product contact utility systems (steam, hot water, compressed air) in food plants.

• Full-lift design ensures rapid pressure reduction in case of control system failure.

🔹 Pharmaceutical and Laboratory

• Used on small autoclaves, sterilizers, and clean steam generators.

• Copper construction avoids rust contamination.

• Manual lever allows validation of set pressure during equipment qualification.

Technical Specifications

Material Breakdown – A28W-16T

Dimensions (Typical – DN20/G3/4″)

Contact us for detailed dimensional drawings for your specific size and thread type.

Performance Parameters

Selection Guide: How to Choose the Right A28W-16T Valve

To select the correct A28W-16T safety valve for your application, answer these six questions:

1. What is your system’s maximum allowable working pressure (MAWP)?

• The safety valve set pressure must be ≤ MAWP.

• For A28W-16T, maximum set pressure is 1.6 MPa (16 bar / 232 psi).

2. What is your normal operating temperature?

• A28W-16T is rated for ≤200°C.

• For temperatures above 200°C, consider a high-temperature valve with a radiator (contact us).

3. What is the medium?

• Water, air, steam, or non-corrosive gases → Standard A28W-16T (brass) works perfectly.

• Corrosive media → Consider A28W-P (304 stainless steel) or A28W-R (316 stainless steel).

4. What thread type and size do you need?

• Check your existing piping: Is it BSP (G or R), NPT, or something else?

• Measure the nominal diameter (DN) or inch size.

5. What set pressure do you require?

• Specify the exact pressure at which the valve must open.

• We can factory-set to any pressure within the 0.1-1.6 MPa range.

6. Will you need to perform manual testing?

• The A28W-16T includes a test lever as standard – ideal for safety code compliance.

• If you don’t need a lever, consider the A27W-16T (micro-lift, no lever).

Quick Selection Table

Comparison: A28W-16T vs. A27W-16T

Both valves are all-copper, threaded, and rated for 16 bar/200°C. The key differences:

Recommendation: For compressed air and steam, choose A28W-16T. For water-only systems with low flow requirements, A27W-16T may suffice.

Why Choose Shanghai WUYUE Pump Valve Group Co., Ltd.?

Shanghai WUYUE Pump Valve Group Co., Ltd. has been engineering and manufacturing safety valves since 2002. Here’s why global customers trust us for their A28W-16T and other safety valve needs:

✅ Specialized Copper Valve Expertise

We understand the nuances of copper alloy casting, machining, and assembly. Our copper safety valves feature:

• Precision-machined seats for bubble-tight shut-off.

• Corrosion-resistant spring coatings (fluoroplastic/PTFE) to prevent spring failure.

• Smooth-operating test levers – no binding or sticking.

• 100% factory testing of set pressure, seat leakage, and lever operation.

✅ Full Customization Capabilities

No two applications are identical. We offer:

• Custom set pressures – any value between 0.1 and 1.6 MPa.

• Custom thread types – NPT, BSP, BSPT, metric, or specials.

• Custom materials – all-brass, all-bronze, or stainless steel internal trim.

• Custom dimensions – if you have a space constraint, we can adjust.

✅ Rigorous Quality Control

Each A28W-16T valve undergoes:

• Set pressure test – verified on computerized test bench (accuracy ±1%).

• Seat leakage test – zero visible leakage at 90% of set pressure (per API 527).

• Hydrostatic body test – 1.5x rated pressure for 3 minutes.

• Spring compression test – to verify consistent force.

• Lever operation test – smooth movement without binding over 50 cycles.

✅ Global Compliance & Export Experience

We routinely ship to over 40 countries and can provide:

• Certificates of Origin (Form E, CO, etc.)

• Third-party inspection (SGS, BV, TÜV, DNV) upon request.

• Manufacturing to international standards (ANSI/ASME, JIS, DIN, GOST, BS).

• CE/PED documentation for European customers.

✅ Competitive Pricing & Fast Delivery

• Direct factory pricing – no middlemen markups.

• Typical lead time – 15-25 days for standard A28W-16T valves.

• Sample orders – 1-5 units available for qualification testing.

• Stock program – common sizes (DN20/DN25, set pressure 8-10 bar) available for immediate shipment.

✅ Responsive Customer Support

Email foreign_trade@0086pv.com and you will receive a reply within 24 hours – often with a quotation, technical drawing, and delivery timeline.

Installation and Maintenance Tips for A28W-16T Valves

Installation Best Practices:

1. Mount vertically – with the valve stem pointing straight up.

2. Keep inlet pipe short – within 10x pipe diameter of the protected vessel.

3. No isolation valves – never install a shut-off valve between the protected equipment and the safety valve.

4. Provide discharge piping – direct outlet to a safe location (floor drain, outside atmosphere).

5. Use thread sealant – apply PTFE tape or pipe dope to male threads only (not on valve threads).

6. Ensure lever clearance – allow enough space to operate the test lever fully.

Weekly Manual Testing Procedure (Required by Many Safety Codes):

1. Slowly pull the test lever to the fully open position.

2. Listen for a clean “pop” or “hiss” – this confirms the disc is lifting off the seat.

3. Observe discharge – media should flow freely from the outlet.

4. Release the lever slowly – the valve should reseal tightly.

5. Verify no continuous leakage after release.

Monthly Visual Inspection:

• Check for visible corrosion, especially around the spring and stem.

• Look for signs of leakage (water stains, rust trails, hissing sounds).

• Ensure the test lever moves freely without excessive force.

Annual Maintenance:

• Remove valve and send to certified lab for set pressure recalibration.

• Inspect seat and disc for wear or debris damage.

• Check spring for corrosion or loss of tension.

• Replace PTFE disc insert if worn.

Signs Your Valve Needs Replacement:

• Continuous weeping or dripping from outlet.

• Valve fails to open during manual test.

• Valve hisses continuously after manual test (failure to reseat).

• Visible corrosion or pitting on the body or spring.

• Set pressure has drifted more than ±5% from factory setting.

Ordering Information – How to Purchase A28W-16T Safety Valves

Step 1: Visit the Product Page

🔗 A28W-16T Spring Slightly Open Unclosed Safety Valve

Step 2: Prepare Your Specification

Use this checklist when emailing us:

• Quantity required

• Set pressure (MPa / bar / psi)

• Inlet thread type and size (e.g., G1/2″, 1/2″ NPT)

• Outlet thread type and size (if different from inlet)

• Medium (water, air, steam, other)

• Operating temperature (°C)

• Any special certifications needed (CE, ASME, etc.)

• Do you need a test lever? (Included as standard on A28W-16T)

Step 3: Email Your Inquiry

Send your specification to: foreign_trade@0086pv.com

Step 4: Receive Quote & Drawing

Within 24 hours, you will receive:

• Commercial quotation (EXW, FOB Shanghai, or CIF your port)

• Dimensional drawing

• Material certificate (if requested)

• Lead time and payment terms

Step 5: Sample Order (Recommended)

For first-time customers, we strongly recommend ordering 1-5 units as samples for field testing before bulk purchase.

Frequently Asked Questions (FAQs)

Q1: Is the A28W-16T suitable for drinking water systems?

A: Yes. The all-copper construction is safe for potable water and will not introduce rust or contaminants. It meets NSF/ANSI 61 requirements for drinking water system components.

Q2: How often should I manually test the valve using the lever?

A: Most safety codes (ASME, PED, Chinese boiler regulations) require weekly manual testing for safety valves on compressed air and steam systems. Check your local regulations.

Q3: Can I adjust the set pressure myself?

A: No. Safety valves are factory-set and sealed. Field adjustment may damage the valve and void the warranty. Contact us if you need a different set pressure.

Q4: What is the difference between “all-copper” and “internal copper”?

A:

• All-copper: The entire body and wetted parts are copper alloy.

• Internal copper: The outer body is cast iron or steel, but all internal wetted parts (seat, disc, stem) are copper. This is a lower-cost option.

Q5: Can the A28W-16T handle oil in compressed air?

A: Yes. Trace amounts of oil from a lubricated air compressor will not harm the brass construction. For oil-free applications, the standard valve works fine.

Q6: What is the difference between “slightly open” and “full-lift”?

A: In some literature, “slightly open” is used interchangeably with “full-lift” for this valve series. The A28W-16T is a true full-lift valve – the disc lifts completely off the seat at set pressure.

Q7: Do you offer CE certified valves?

A: Yes. Upon request, we can provide A28W-16T valves with CE marking and PED (Pressure Equipment Directive) documentation for European customers.

Q8: What is your warranty?

A: We offer a 12-month warranty against manufacturing defects from the date of shipment. The warranty covers replacement of defective valves but does not cover wear parts (disc insert, PTFE seal) or damage from debris/improper installation.

Q9: Can I get a valve with stainless steel internal parts instead of brass?

A: Yes. Contact us for a “P” (304 stainless) or “R” (316 stainless) version.

Q10: What is the maximum pressure the body can withstand?

A: The A28W-16T body is hydrostatically tested to 2.4 MPa (24 bar / 350 psi) – 1.5x the nominal pressure rating.

Troubleshooting Common Problems

Conclusion: Trust Shanghai WUYUE for Your A28W-16T Safety Valve Needs

The A28W-16T safety valve combines the corrosion resistance of copper alloy with the high flow capacity of a full-lift design and the convenience of a manual test lever. Whether you are protecting an air compressor, a steam generator, or a hot water heater, this valve provides dependable overpressure protection at temperatures up to 200°C.

Shanghai WUYUE Pump Valve Group Co., Ltd. brings over two decades of manufacturing experience, rigorous quality testing, and a commitment to customer satisfaction. We don’t just sell valves – we provide safety solutions tailored to your specific operating conditions.

Ready to order? Contact us today.

📧 Email: foreign_trade@0086pv.com
🌐 Website: https://www.021pv.com
🔗 Product Page: A28W-16T Spring Slightly Open Unclosed Safety Valve

Shanghai WUYUE Pump Valve Group Co., Ltd.
Your Trusted Partner in Pressure Safety – Since 2002

© Copyright 2002-2026 | Shanghai WUYUE Pump Valve Group Co., Ltd. | All Rights Reserved | ICP:09023850-8

Disclaimer: Specifications are subject to change without notice. Please confirm all details with our sales team before ordering.