HHSV Safety Relief Valve Range
Industrial Safety Valves and Pressure-Relief Solutions
Explore HHSV spring-loaded, pilot-operated, safety reflux, impulse and main, and vacuum safety valves. Compare the product series below, then share your medium, temperature, operating and set pressures, required capacity and connection details for selection.
Product Architecture
Safety Valves and Pressure-Protection Functions
Table of Contents
How the Range Is Structured
Choose by Operating Principle and Protection Duty
Start with the pressure condition and equipment to be protected. Then compare the relevant operating principle, lift type, connection and service limits on the individual product pages.
01 · Relief-Valve Operating Families
Spring-loaded and pilot-operated valves provide overpressure protection. Impulse and main safety valves operate together as a coordinated system.
02 · Special Pressure-Control Functions
Safety reflux valves protect liquid-phase return lines at LPG station pump outlets. Vacuum safety valves admit air when negative pressure reaches the specified condition.
03 · System Selection
Review valve arrangement, connecting pipework and required documentation together with the selected products and service conditions.
Product Family Explorer
Explore Valve Families and System Selection
Compare the published product series by protection duty. Full lift, low lift, closed or enclosed construction, spanner operation, external threads and duplex assemblies are identified within the relevant series.
Operating family
Spring-Loaded Safety Relief Valves
Spring-loaded safety valves for equipment and pipeline overpressure protection, including full lift, low lift, external-thread, air-compressor and duplex assembly designs.
Product Series
A21H/A21W/A21F, AQ-20, A41H/A41Y, A42Y, A44Y, A47H/A47Y, A48Y and A37H/A38Y/A43H. Pressure groups and service limits vary by series.
Operating family
Pilot-Operated Safety Relief Valves
A pilot controls the main valve to provide overpressure protection for pressure equipment, vessels and pipelines.
Product Series
A46 Pilot Operated Safety Valve: PN16/25/40 and PN64/100/160 versions.
Special function
Back-Flow / Safety Reflux Valves
Safety reflux valves for overpressure protection of liquid-phase return lines at LPG station pump outlets.
Product Series
AH42F Safety Reflux Valve (PN16/25/40) and AHN42F-P18 Parallel Safety Reflux Valve.
Operating system
Impulse & Main Safety Valve Systems
An impulse safety valve operates the main safety valve to protect power plant boilers, pressure vessels, and pressure and temperature reducing equipment.
Product Series
A49H-40 Main Safety Valve with GA49H-4.0 DN25 Impulse Safety Valve.
Special function
Vacuum Safety Valves
HFA72W vacuum safety valves automatically admit air to protect vessels against excessive negative pressure.
Product Series
HFA72W-10-P/R Vacuum Negative Pressure Safety Valve. Refer to the product page for its size, pressure rating and temperature limits.
Engineering topic
Safety Relief System Selection
Discuss the valve arrangement, connecting pipework and supporting documentation required for your pressure-protection system.
Selection Inputs
Share the process duty, equipment layout and maintenance requirements so the proposed arrangement can be reviewed.
Product Family & Series Guide
Compare HHSV Product Series
Choose a product series, then open the pressure group or version that matches your requirement.
Swipe to compare product families.
| Product Family | Representative Series and Products | Configurations and Selection Considerations |
|---|---|---|
| Spring-Loaded | A21H / A21W / A21F; AQ-20; A41H; A41Y; A42Y (PN16/25/40 / PN64/100); A44Y (PN16/25/40 / PN64/100); A47H; A47Y; A48Y (PN16/25/40 / PN64/100); A37H / A38Y / A43H | Full / low lift · Closed or enclosed designs · With spanner · External thread or flanged connections · Duplex assemblies with two valves on a Y-type joint. |
| Pilot-Operated | A46 Pilot Operated Safety Valve (PN16/25/40 / PN64/100/160) | Pilot and main-valve arrangement · Pressure group · Inlet / outlet sizes · Medium and temperature. |
| Back-Flow / Safety Reflux | AH42F Safety Reflux Valve; AHN42F-P18 Parallel Safety Reflux Valve | Liquid-phase return-line relief at LPG station pump outlets · Model-specific connection dimensions and operating limits. |
| Impulse & Main | A49H-40 Main Safety Valve + GA49H-4.0 DN25 Impulse Safety Valve | Main / impulse valve roles · Steam service · Connecting pipework and installation requirements. |
| Vacuum Safety | HFA72W-10-P/R Vacuum Negative Pressure Safety Valve | Negative-pressure protection by air admission · DN15–DN200 · Temperature up to 200°C · PN10 pressure rating. |
Sizes, materials and operating limits vary by model. Open a product link for its specifications. PN10 is the pressure rating, not a vacuum set point.
Pressure Direction and Protection Duty
Return-Line Overpressure and Vessel Vacuum Require Different Valves
AH42F and AHN42F-P18 serve liquid-phase return lines at LPG station pump outlets. HFA72W addresses negative pressure in vessels. Choose the relevant function before comparing sizes and ratings.
Safety Reflux Valves
When pressure exceeds the specified value, AH42F and AHN42F-P18 open to return liquid and protect the equipment and pipework.
Vacuum Safety Valve
HFA72W opens to admit air when the specified negative-pressure condition is reached, helping protect the vessel against excessive vacuum.
PORTFOLIO-WIDE MANUFACTURING CAPABILITY
Broad Manufacturing Capability, Matched to Your Exact Service.
These figures describe HHSV’s portfolio-wide manufacturing capability. Individual product series have narrower size, pressure and temperature limits; the values below are not a combined rating for every listed model. Confirm the selected configuration against its product data, pressure-temperature rating and applicable certification scope.
Overall size envelope
DN10-600
1/2-24 in
Overall pressure envelope
0.6-42 MPa
Class 150-2500
Overall temperature envelope
−196 to 570°C
Model / material dependent
Media
Steam · Gas · Liquid
Service and model dependent
Materials
Carbon · alloy · stainless
Duplex / special alloys by product
Connections
Flanged · threaded · other
Series / drawing dependent
Sizing & Backpressure
Start with the Required Protection Duty and Service Conditions
Provide medium/phase, required capacity or protection duty, operating and set pressure, relieving temperature, superimposed/built-up backpressure, connection, material and applicable code. API 520 or ISO 4126 sizing is used where appropriate to the selected product and project.
For liquid-phase return lines at LPG station pump outlets, review the AH42F and AHN42F-P18 reflux valves. For vessel vacuum protection, review HFA72W. Confirm the connection, pressure conditions and required capacity for the selected duty.
Buyer Path
Move from function to evidence in four steps.
01 · Choose family
Identify overpressure, liquid return-line relief or vessel vacuum protection.
02 · Review Product
Compare the models, pressure groups and published dimensions in the relevant product family.
03 · Engineering selection
Confirm capacity, pressures, temperature, backpressure, materials, standards and documentation.
04 · Request a Quote
Receive the selected model, sizing basis, deviations, drawings, test/certificate scope and delivery boundary.
Standards, Testing & Certification
Confirm the Design Standard, Test Records and Certification Scope
HHSV connects the selected model with the project standard, required test records and applicable certification or authorization scope in the technical quotation package.
API 520
Sizing, selection and installation basis where applicable to the product/project.
API 526
Flanged steel pressure-relief dimensions/orifice conventions only for series that use the standard.
API 527
Seat-tightness test basis where specified; it is not a product certification statement.
ISO 4126
Safety-valve design/sizing/testing requirements where applicable to the selected series.
ASME BPVC
ASME Section VIII requirements may be used where applicable. Any UV or National Board marking is confirmed for the exact proposed valve and current authorization scope.
GB/T 12241 / 12243
Leaflet-listed Chinese product-standard basis for applicable safety-valve series.
Designed to
The stated code/standard is used as the design, sizing or dimensional basis for the selected model.
Tested in accordance with
The supplied valve is tested using the stated method and acceptance criteria for the agreed scope.
Certified to
Only use when the legal entity, factory, model, pressure range and marking are within the actual certificate/authorization scope.
Testing & Documentation
Documentation for the Selected Valve
Depending on product and contract scope, HHSV can provide material records, serial-number traceability, pressure/set testing, reseating evidence, API 527 leakage records where applicable, dimensional drawings, datasheets, sizing calculations, inspection documents and final MDR deliverables.
Industrial Applications
Match the Valve to the Application and Service Conditions
Application suitability is confirmed by matching the service medium, capacity, pressure, temperature, materials and compliance requirements to the selected valve series.
Power Generation
Steam, boiler and pressure-system protection with code- and model-specific verification.
General Industrial
OEM, compressor, vessel and packaged-equipment protection across gas/liquid/steam services.
Oil & Gas Production
Pressure-relief products selected from process duty, backpressure, materials and owner requirements.
Refining & Petrochemical
Select the valve and system arrangement from the process duty, backpressure, material compatibility and project requirements.
Chemical & Process
Material compatibility, leakage, toxic/corrosive service and documentation can control the selection.
Special Service
Discuss temperature limits, vacuum conditions, material compatibility and the documentation required for the proposed service.
Start with the Protection Requirement
Send the RFQ, datasheet, process specification or existing valve nameplate.
HHSV can identify missing service inputs, route the enquiry to the correct family, complete sizing/configuration review and return an approvable technical quotation package.