Important: What Does “1 Inch” Mean in the 1″ Santoprene Diaphragm Pilot Hole?
The “1 inch” refers to the valve inlet size — the pipe connection diameter. It does not describe the diaphragm itself. The diaphragm measures 2-1/2″ in diameter. If you have a 1-1/2″ inlet valve, see our 72-DS-P Santoprene diaphragm instead.
What Is the 71-DS-P?
The 71-DS-P is a Santoprene replacement diaphragm for 1″ inlet float valves with a pilot hole for pressure-assisted operation. It fits Cleveland Valve Company S2-100 series valves, Greenlawn sprinkler float valves, and Hydro-Gardens float valves. Additionally, it is a direct drop-in for the S2-100P pilot float valve.
Standard urethane diaphragms work well in plain water. However, they break down quickly when exposed to chemicals, detergents, or high heat. The 71-DS-P uses Santoprene thermoplastic vulcanizate (TPV) to handle those tougher conditions.
What Does the Extra Hole Do?
The pilot hole — sometimes called a bleed hole — changes how the valve operates. Without it, the float must overcome full line pressure to close the valve. The extra hole allows a small amount of water to pass through to the top side of the diaphragm. As a result, pressure acts on both faces and the float closes the valve much more easily.
Why That Matters
In a pilot-assisted valve, higher supply pressure actually helps seat the valve harder. This means better shutoff at high pressure — less drip and weep compared to a standard diaphragm. Additionally, the controlled bleed dampens diaphragm movement. Consequently, you get quieter fill and less water hammer in tanks and cisterns.
The pilot hole also extends the functional pressure range of the valve. However, keep in mind that the Santoprene compound is rated to 80 PSI maximum. For applications above 80 PSI, use the urethane 71-D-P instead.
Built for Car Wash Systems
Car wash operators deal with pre-soak, soap, and rinse aid solutions daily. As a result, standard diaphragms wear out fast. The 71-DS-P resists chemical attack from acids, bases, and solvents. Furthermore, it holds up in elevated temperatures that would degrade a standard urethane diaphragm. This means fewer replacements and less downtime.
Greenlawn and Hydro-Gardens Replacement
Both Greenlawn and Hydro-Gardens are out of business. Consequently, finding quality replacement diaphragms has become difficult. The 71-DS-P fits the same 1″ inlet valve body used in both brands. It is therefore a reliable option for irrigation systems that handle liquid fertilizers, herbicides, or other chemical solutions at variable or higher pressures.
When To Choose the Pilot Hole Version
- Variable or higher inlet pressure (above ~40 PSI)
- Municipal water supply connections
- Elevated storage tanks
- Any application where the standard diaphragm struggles to close fully
- Chemical or car wash systems with pilot-assisted float valves
Material Properties
- Excellent resistance to acids, bases, and chemical solvents
- Operating temperature range: 34°F to 300°F (water applications)
- Santoprene compound rated to -60°F for non-water applications
- Suitable for chlorinated water, fertilizer, and chemical dosing systems
- Good compression set resistance for reliable long-term sealing
- UV and ozone resistant
- Max working pressure: 80 PSI
Which Diaphragm Do You Need?
All four diaphragms fit the same 1″ inlet valve body. The right choice depends on your water type and system pressure.
| SKU | Material | Pilot Hole | Max PSI | Best For |
|---|---|---|---|---|
| 71-D | Urethane | No | 150 PSI | General water, irrigation, livestock tanks |
| 71-D-P | Urethane | Yes | 150 PSI | High pressure, municipal supply, pilot-assisted operation |
| 71-DS | Santoprene | No | 80 PSI | Car wash, chemical dosing, fertilizer systems |
| 71-DS-P | Santoprene | Yes | 80 PSI | Chemical systems with pilot-assisted valve operation |
Santoprene pressure warning: Santoprene diaphragms (71-DS and 71-DS-P) are rated to 80 PSI maximum. Santoprene is a softer compound than urethane and is more prone to failure at higher pressures. Do not use in high pressure applications. If your system exceeds 80 PSI, use the urethane 71-D or 71-D-P instead.
Cleveland Valve Company has manufactured float valve parts in the USA since 1980. With Greenlawn and Hydro-Gardens no longer in production, CVC is one of the few remaining sources for quality replacement diaphragms for these valve bodies.
