Overview
The Ham-Let H-300-SS-L-R-3/8-M is a high-performance instrumentation needle valve engineered for demanding hydraulic and pneumatic applications. This model features 316 stainless steel construction with an integral bonnet design that provides superior sealing and durability. The H-300 series delivers precise flow control and long service life, making it ideal for critical shut-off and regulation duties in industrial instrumentation panels.
Key Features
- 5000 psi (345 bar) maximum working pressure — rated for high-pressure instrumentation service
- Stainless steel and brass construction — corrosion-resistant for harsh environments
- Integral bonnet design — ensures optimal sealing and reduced assembly complexity
- Regulating stem with metal bar handle — smooth, precise flow adjustment
- Let-Lok 3/8″ fittings — leak-free compression connections
- Packing bolt design — enables easy panel mounting without disassembly
- Chevron stem packing — minimizes operating torque and wear
- Belleville washers — automatically compensate for packing wear over time
Technical Specifications
- Model: H-300-SS-L-R-3/8-M
- Series: H-300
- Inlet/Outlet Size: 3/8″ Let-Lok (compression)
- Body Material: 316 Stainless Steel
- Maximum Allowable Working Pressure (MAWP): 5000 psi (345 bar)
- Maximum Allowable Working Temperature (MAWT): 446°F (230°C)
- Flow Coefficient (Cv): 0.09 to 1.8
- Stem Type: Regulating (L-R designation)
- Handle Type: Metal Bar (-M designation)
- Connection Type: Let-Lok compression fitting
- Packing Type: Chevron with Belleville washers
- Certification: ISO 15848-1:2006(E) compliant
- Operating Temperature Range: -40°F to 446°F (-40°C to 230°C)
Typical Applications
The Ham-Let H-300-SS-L-R-3/8-M is widely used in:
- Instrumentation and test systems — precision pressure and flow control
- Laboratory equipment — reliable shut-off for sample and calibration lines
- Pneumatic control panels — pilot-operated logic circuits
- Hydraulic manifold systems — metering and regulation stations
- Process automation — critical pressure and flow isolation in high-vibration environments
- Energy and petrochemical industries — corrosion resistance in demanding conditions
Compatibility & Replacements
Compatible With
- Hydraulic and pneumatic systems rated to 5000 psi
- Instrumentation manifold blocks with 3/8″ Let-Lok ports
- High-pressure test benches and laboratory equipment
- ISO 4401 (CETOP-05) compliant valve cavity configurations
- Systems requiring -40°C to +230°C temperature performance
Replaces / Drop-In Replacement For
- Ham-Let H-300U-SS-L-R-3/8-M (equivalent modern designation)
- Swagelok SS-1RS6 (similar performance equivalent)
- Various OEM instrumentation needle valves rated to 5000 psi with 3/8″ Let-Lok fittings
Works With
- Fitting Standards: Let-Lok compression fittings (3/8″ OD tubing)
- Pressure Systems: Hydraulic, pneumatic, inert gas, and liquid media
- Integration: Manifold cavity mounting, panel-mounted instrumentation
- Media Compatibility: Mineral oils, synthetic fluids, water-glycol, compressed air, nitrogen, argon
















