High Sample Temperature Shutoff Valve Overview
Process analyzers and sample conditioning equipment require sample fluids to remain within their allowable temperature limits. Low cooling water flow, sample cooler failure, or unusually high process temperatures can allow overheated fluid to reach sensitive downstream instrumentation.
The HST high temperature shutoff valve automatically shuts off sample flow in response to excessive fluid temperatures, protecting expensive and delicate analyzers from overheating. Unlike electrically actuated shutoff valves, the HST requires no external power, wiring, or controls, providing a cost-effective alternative that simplifies installation and reduces associated component costs.
Design Features
- Exclusive Thermoloid® paraffin wax thermal actuator
- Ram-type plug provides tight shutoff
- Operating temperatures unaffected by variable inlet pressures
- Wide choice of temperature set-points available
- Corrosion-resistant – all stainless-steel construction
Typical Applications
- Sample Cooler Outlet Lines: Functions as a sample cooler shutoff valve when reduced cooling performance allows sample temperatures to exceed acceptable limits.
- Steam and Water Analysis Systems (SWAS): Protects analytical instruments that require cooled steam and water samples.
- Process Analyzer and Sample Conditioning Systems: Prevents overheated process samples from reaching temperature-sensitive measurement equipment.
Technical Documents
Specifications
- Size: ½”
- Maximum Operating Pressure: 3000 PSIG (207 bar)
- Maximum Temperature: 300°F (149°C)
- Body Material : 303 SS and 316/316L SS options
Ordering
| Part Number | Description3,4 |
|---|---|
| 254-000000-XXX | ½ HST-XXX-SS-E |
| 254-001000-XXX | ½ HST-XXX-SS-V |
| 254-002000-XXX | ½ HST-XXX-SS-K |
| 254-110000-XXX | ½ HST-XXX-S6-E |
| 254-111000-XXX | ½ HST-XXX-S6-V |
| 254-112000-XXX | ½ HST-XXX-S6-K |
Ordering & Configuration Notes
- Body rating: 3000 PSIG at 600°F (207 bar at 315.6°C).
- Full open temperatures “XXX” available: 100°F, 105°F, 115°F, 120°F, 125°F, 130°F, 140°F, 170°F, 185°F. Other temperatures are available upon request.
- Closing temperature is typically 10°F above opening temperature.
- Seal material compatibility:
- E – EPDM – air, water, steam, ketones, and synthetic hydraulic oils
- V – Viton® – air, fuel, oil, gas and petroleum-based hydraulic oils
- K – Kalrez® – Special order option
- Valve material:
- SS – 303 stainless steel
- S6 – Dual Grade 316/316L stainless steel
How the HST Valve Works
The HST is a normally open valve installed in the sample line between the sample cooler outlet and the downstream analyzer or instrument. Its internal thermal actuator continuously responds to the temperature of the sample fluid passing through the valve.
Under normal operating conditions, the valve remains open to allow sample flow. As the fluid temperature rises, the valve modulates toward its closed position. The valve closes approximately 10°F above its specified full-open temperature, preventing overheated samples from reaching downstream instrumentation.
As the sample temperature decreases, the valve automatically reopens, restoring flow to downstream instrumentation.
