Why the Aquatrol 88 Series Is the Compact ASME Safety Valve Standard
The Aquatrol 88 Series is a compact bronze-body safety relief valve designed for air, gas, and other compressible fluid service. It is ASME Section VIII (“UV”) certified and National Board (NB) registered, making it suitable for code-compliant pressure relief on unfired pressure vessels including air receivers, compressors, accumulators, small process tanks, and pneumatic systems. Aquatrol has manufactured safety and pressure relief valves in the United States since 1947, and the 88 Series is one of their highest-volume product families for low-flow industrial applications.
This guide covers what an engineer or procurement professional needs to know to specify and order an 88 Series valve: available sizes and connections, seat materials, set pressure ranges, ASME certifications, application fit, and the five data points required to size it correctly. As an authorized Aquatrol distributor, we stock the most common 88 Series configurations for next-business-day shipping.
Available Sizes and Connections
The 88 Series is engineered for compact installations where larger 740-class valves would be oversized or impractical. Standard inlet sizes:
- 1/2″ NPT — the most common configuration, suitable for most compressed air receivers and small process vessels
- 3/4″ NPT — mid-range capacity for higher-flow compressed air or gas systems
- 1″ NPT — the largest standard size in the 88 family, for higher relieving capacity
Outlet connections are typically NPT female and sized to match or exceed the inlet. Configurations available from stock at Safety Control Valves include 1/2″ x 1/2″, 1/2″ x 3/4″, and 1″ x 1″ NPT.
Seat Material and Body Construction
The 88 Series uses a metal seat as standard — the right choice for clean dry air and gas service where elastomer seats would be unnecessary or unsuitable. Metal seats provide:
- Higher temperature tolerance compared to elastomer seats
- Long service life on dry, non-corrosive media
- Predictable reseating after relief events
The body and trim are bronze, suitable for non-corrosive air, nitrogen, and most non-corrosive industrial gases. For corrosive gas service or specialty applications, consider the Aquatrol 740 Series or 700-class stainless steel models instead.
ASME Section VIII Certification and National Board Registration
Every Aquatrol 88 Series valve we ship carries:
- ASME UV stamp — certifying the valve meets ASME Boiler and Pressure Vessel Code (BPVC) Section VIII, Division 1 requirements for unfired pressure vessels
- National Board registration — with NB-certified relieving capacity, required for legal use on ASME code vessels in most U.S. and Canadian jurisdictions
For background on what ASME Section VIII compliance actually requires, see our ASME Section VIII Compliance Guide. To verify the certifications stamped on your valve, see How to Read a Safety Valve Nameplate.
Set Pressure Range
The 88 Series covers the most common low-to-mid set pressure ranges for compressed air and industrial gas applications. Set pressure is established and certified at the factory and stamped on the nameplate. Specific pressure ratings depend on the model and configuration — confirm with the spec sheet for your application or request a quote with your required set pressure and we will match you to the correct part number.
Note: ASME-certified set pressures are not field-adjustable. If you need a different set pressure than what is currently stamped on a valve, the valve must be returned to an authorized facility for re-setting and re-stamping.
How to Size an 88 Series Valve
Sizing a pressure relief valve is the engineer’s most important spec’ing decision. Under-sized means the valve cannot relieve the worst-case overpressure event — a code violation and a safety hazard. Over-sized means chatter, premature wear, and unnecessary cost. The five inputs you need:
- Required relieving capacity in SCFM (air/gas) — calculated from your worst-case overpressure scenario per ASME Section VIII
- Set pressure in psig — typically 90% of MAWP or as specified by the system designer
- Maximum back pressure — if the valve discharges to atmosphere this is zero, but if discharging into a header system this matters
- Service fluid — air, nitrogen, natural gas, etc. (specific gravity affects capacity)
- Operating and relief temperature — affects materials and capacity
For a step-by-step walk-through with worked examples, see our forthcoming How to Size a Pressure Relief Valve guide. For 88 Series-specific sizing assistance, send us your five data points and we will recommend the correct model.
Common Applications
The 88 Series fits where you need ASME-certified pressure relief on a small to mid-flow air or gas system:
- Compressed air receivers in industrial and commercial facilities
- Reciprocating and rotary screw compressor packages
- Small accumulators and surge tanks
- Pneumatic actuator systems and control air panels
- Nitrogen blanket systems on small vessels
- Inert gas systems in laboratories and process plants
Cross-Reference and Replacement
If you are replacing an existing 88-class valve from another manufacturer (including discontinued Kingston models), use our Cross-Reference Tool to find the equivalent Aquatrol part number. The five data points stamped on your existing valve’s nameplate — set pressure, capacity, size, service, certification — are all you need to identify the correct replacement.
For step-by-step instructions on cross-referencing, see How to Cross-Reference and Replace Any Safety Valve with an Aquatrol Equivalent.
Ordering Information
To order an Aquatrol 88 Series valve, you will need:
- Inlet size and connection — 1/2″, 3/4″, or 1″ NPT
- Outlet size — typically same as inlet or one size larger
- Set pressure in psig
- Service — air, gas, or specific fluid name
- Required relieving capacity in SCFM
Browse 88 Series inventory in our Aquatrol product catalog or request a quote with your application details. As an authorized Aquatrol distributor, we sell at factory-direct pricing with most standard configurations shipping next business day.
Frequently Asked Questions
What is the difference between the 88 Series and the 740 Series?
The 88 Series is compact and bronze-bodied, optimized for low-to-mid flow air and gas service in sizes from 1/2″ to 1″ NPT. The 740 Series covers a broader range of services (air, gas, liquid, steam) in sizes from 1/2″ to 3″ with multiple seat materials and body options. Use the 88 for small, simple air/gas applications; use the 740 family when you need higher capacity, alternate seat materials, or non-air service.
Is the 88 Series field-repairable?
ASME-stamped relief valves are not field-adjustable for set pressure. Routine internal maintenance and parts replacement should be performed by an authorized repair facility that maintains the valve’s ASME and NB certification. Non-authorized repair voids the certification and disqualifies the valve from code installations.
What is the lead time for 88 Series valves?
Standard configurations stocked at Safety Control Valves typically ship next business day. Non-stock configurations (specific set pressures, special materials) are built to order; lead time depends on Aquatrol’s production schedule. Contact us with your specifications for a current lead time.
What is Aquatrol’s warranty?
Aquatrol provides a manufacturer warranty on all 88 Series valves purchased through authorized distributors. As an authorized distributor, valves shipped from Safety Control Valves carry the full Aquatrol warranty. See current warranty terms on the Aquatrol spec sheet or contact us for details.
Can I use an 88 Series valve on a steam system?
No. The 88 Series is not designed or certified for steam service. For steam applications, use the Aquatrol 132 Series (ASME Section VIII Steam) or the 742 stainless steel model. See our Steam Safety Valves guide for steam-specific selection criteria.