Graco 15A204 Piston – Precision Regulator Component
The Graco 15A204 Piston is a critical internal component of Graco regulator assemblies, designed to deliver high-precision control of fluid pressure. As the moving core of the regulator’s valve mechanism, this piston plays a pivotal role in ensuring accurate, repeatable response to spring and diaphragm forces, contributing directly to consistent downstream pressure performance.
Product Overview
The 15A204 Piston is engineered to exacting OEM standards to ensure perfect mating with regulator seats, diaphragms, springs, and housings. It is crafted from materials and toleranced to provide minimal friction, reliable sealing, and long service life even under demanding conditions of fluid flow, cycling loads, and variable pressures. Through its action of moving in response to spring or air forces and opening or closing the fluid path, it maintains the regulator’s setpoint and prevents pressure drift or instability.
Key Features
- OEM-specified component — Part Number: 15A204
- Precision-machined piston core for smooth travel and minimal stiction
- Reliable sealing interface with the valve seat to maintain pressure integrity
- Durable material selection designed for high-cycle life and fluid compatibility
- Direct fit for Graco regulator models requiring that piston, ensuring compatibility and performance
Technical Specifications
| Part Number |
15A204 |
| Description |
Piston — Valve Core for Regulator |
| Function |
Translates spring/diaphragm force into fluid flow control |
| Material |
Engineered alloy or stainless steel (OEM spec) with seal interface |
| Application |
Fluid or back-pressure regulator assemblies in Graco systems |
Compatible Systems
- Graco pneumatic regulator models that list “Piston – 15A204” in their parts breakdown
- Graco fluid pressure or back-pressure regulator assemblies where this piston serves as the valve core
Installation Guidelines
Proper installation of the Graco 15A204 Piston is essential for maintaining regulator accuracy and long-term reliability:
- Depressurize and drain the regulator before disassembly.
- Disassemble the regulator body to access the piston area, noting orientation and any seals.
- Remove the existing piston carefully and inspect the sealing surface and seat for wear or damage.
- Install the new 15A204 piston, ensuring smooth movement and correct seating against the valve surface.
- Reassemble the regulator, replacing any worn seals, O-rings or springs as needed.
- Repressurize the system slowly and test the regulator for correct setpoint and stability before returning to full service.
Maintenance Advice
- Inspect the piston and surrounding seat during routine regulator maintenance or when pressure performance degrades.
- Check for signs of scoring, grooves, or pitting on the piston surface or valve seat.
- If any damage is found, replace the piston with the 15A204 OEM part and inspect associated seals and springs.
- Clean and lubricate mating surfaces per manufacturer guidelines before reassembly.
Frequently Asked Questions
It moves in response to spring or diaphragm force to open or close the fluid path in the regulator, helping maintain accurate downstream pressure.
Yes — it is a factory-specified piston component designed for compatibility with Graco regulators and ensures proper performance when installed correctly.
Replace the piston when you observe pressure instability, leakage, or visible wear on piston surfaces or valve seat. Proactive replacement can restore regulator accuracy and prevent downtime.
After installing the new piston, repressurize the system slowly, set the regulator to the desired pressure, and monitor for stable performance without drift or leakage.
