CNST Safety  Relief Valve A21H-16C A21W-16P DN15/25/32/40/50/65/80

This is a spring‑loaded micro‑lift external‑thread safety relief valve by CNST, designed to automatically vent excess system pressure and protect pressure‑bearing equipment and pipelines from over‑pressure damage for gas, liquid and steam media. It solves the risk of vessel or pipeline rupture, equipment failure and safety hazards caused by unexpected pressure spikes in low‑to‑medium‑pressure industrial systems.

Product Information

Product Features

• Spring‑operated micro‑lift opening mechanism, partial‑stroke discharge for stable, precise pressure relief, reduces unnecessary medium loss
• External screwed union thread connection for straightforward assembly and disassembly in compact pipeline layouts
• Dual material options: carbon steel for general‑purpose environments, 304 stainless steel for corrosive‑media service
• Automatic operation: triggers relief once pressure exceeds set threshold, auto‑reseats as pressure normalizes, no manual intervention required during normal protection cycles
• Suited for continuous service up to 200°C working temperature for gas and liquid process media
• Multiple DN size selections from DN15 up to DN80 to match different pipeline flow requirements
• Compact body footprint, fits confined equipment and piping spaces

A21H-C type are used for the equipment and pipeline of the air, ammonia, petroleum gas, etc.medium what the working temperature are less than 200℃. A21W-P, R type are used for the equipment and pipeline of the quality with corrode gas and liquid medium what the working temperature are less than 200℃. Take for extrapressure protection devices.

A21F type are used for liquefied petroleum gas what the working temperature are less than 120℃. The valve inlet is set with two types: welded pipe and pipe thread, which shall be calibrated and confirmed before purchase.

Specific Application Scenarios

1. Industrial boiler auxiliary piping: Protect boiler accessory pipelines from dangerous over‑pressure surges for water‑gas mixed working conditions.
2. Liquid & gas pressure storage tanks: Provide over‑pressure safety release for tanks holding non‑corrosive or mildly corrosive process fluids.
3. Compressed‑air and gas compressor downstream pipelines: Prevent pressure build‑up risk in air‑compressor distribution piping networks.
4. Chemical process low‑pressure piping: Stainless‑steel variants safeguard pipelines conveying mildly corrosive liquid or gaseous process media.
5. Heat‑exchange and thermal‑equipment loops: Over‑pressure protection for hot‑water and thermal‑fluid circulation pipe‑work under elevated‑temperature service.

FAQ

Q: What is the main purpose of the CNST A21‑series safety relief valve?

A: The CNST A21‑series spring‑micro‑lift safety relief valve delivers automatic over‑pressure protection. When system pressure surpasses the pre‑set limit, the valve opens to discharge excess pressure, shielding pressure vessels, boilers and pipelines from rupture risk. CNST’s well‑engineered spring mechanism ensures reliable opening and re‑seating performance for long‑term industrial service.

Q: Which material variant should I select, carbon‑steel A21H‑16C or stainless‑steel A21W‑16P?

A: Choose carbon‑steel A21H‑16C (cast steel) for general‑purpose non‑corrosive media such as compressed air, regular water and oil. Pick the A21W‑16P 304‑stainless‑steel variant when working with corrosive gas or liquid. CNST manufactures both variants to deliver consistent sealing performance at temperatures up to 200°C.

Q: What size DN options are offered for this A21 safety relief valve?

A: The CNST A21 threaded safety relief valve covers DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80 nominal diameters. Verify your pipeline dimension and working‑pressure parameters before ordering; reach out for additional specification support if your requirement falls outside standard sizes.

Q: Does this A21 micro‑lift safety valve work for both liquid and gas media?

A: Yes. The CNST Shuangtai A21‑series micro‑lift safety relief valve is suitable for gas, steam and liquid service. Please confirm your exact medium and operating temperature (max 200 °C) when selecting the correct model variant to maintain expected service life and sealing integrity.

Q: Is the A21‑series valve simple to install?

A: Yes. It uses external screwed union thread connections, enabling quick installation in compact piping layouts. The valve must be mounted vertically for proper spring‑spool operation, as recommended by CNST technical guidance.