Graco 127339 Check Valve – 1/8″ MNPT × 1/8″ FNPT
The Graco 127339 check valve is a compact one-way fluid valve designed to maintain directional flow in Graco systems by preventing backflow. Its 1/8″ MNPT to 1/8″ FNPT ports make it ideal for high-precision fluid control applications.
Compatible Graco Machines
This check valve is commonly found in Graco fluid systems and proportioning machines. Typical compatible models include:
- Graco ProMix 2KS Series Proportioners
- Graco Xtreme Mix Proportioners
- Graco Plural-Component Proportioners (2-component systems)
- Graco Metering and Dispensing Systems with small-port check valves
*Compatibility varies by system configuration—refer to your machine’s parts manual to verify.
Key Features
- 1/8″ MNPT (male) to 1/8″ FNPT (female) connections
- Prevents reverse flow in fluid circuits
- Compact and lightweight design
- Genuine Graco OEM part ensures reliability and performance
- Ideal for metering, proportioning, and precision dispensing systems
Technical Specifications
| Part Number | 127339 |
| Connection Inlet | 1/8″ MNPT (Male) |
| Connection Outlet | 1/8″ FNPT (Female) |
| Function | Check Valve (One-way flow) |
| Material | Sturdy metal (OEM grade) |
| Primary Use | Prevent backflow in proportioning & metering systems |
Why Use This Check Valve?
Installing the Graco 127339 ensures consistent, one-directional fluid flow, which protects your system from pressure spikes, backflow, and contamination. It’s a vital component for maintaining precision in plural-component and metering equipment.
Installation & Maintenance Tips
- Ensure the valve is installed in the correct orientation — observe the flow arrow (if present).
- Apply a small amount of thread sealant to NPT threads, but avoid contaminating the valve seat.
- Periodically inspect for debris or build-up inside the valve.
- If blocked or leaking, replace with a genuine Graco check valve to maintain system integrity.
Safety Notes
Always depressurize the fluid system before installing or servicing the check valve. Improper installation can lead to leaks, reversed flow, or component failure.
Frequently Asked Questions
If the check valve fails (e.g., stuck open), backflow can occur, potentially damaging pumps, pressure regulators, or proportioning systems. Replace immediately if performance issues arise.
It’s suitable for many proportioners, metering, and dispensing systems. However, always verify thread size and model compatibility with your Graco parts manual.
The check valve adds minimal pressure drop when flowing in the correct direction. Its main role is to prevent reverse flow, not regulate pressure.
