Engineered to be reliable and contamination free

A Sundyne Sealless Diaphragm Compressor is a combination of two systems - a hydraulic system and a gas compression system. A metal diaphragm group is the isolating component between these two systems. Ultrafram diaphragm technology and proprietary cavity design provide unmatched diaphragm life. Process gas is completely isolated from the environment and the hydraulic system, making this reliable and completely sealless technology, by Sundyne...the industry leaders in sealless pump technology.


The Gas Compression System

The gas compression system consists of three flat metal diaphragms, which are clamped between two precisely contoured cavity plates, and process gas inlet and outlet check valves.

The Hydraulic System

The hydraulic system includes a motor-driven crankshaft that reciprocates a piston in the hydraulic fluid medium. This positive displacement piston pulses the hydraulic fluid against the lower side of the diaphragm group, causing it to sweep the cavity displacing the process gas. The other components of the hydraulic system are the automatic hydraulic injection pump, the hydraulic fluid check valve and the hydraulic overpump valve. In addition to ensuring that the hydraulic system is always full for the compression cycle, the automatic injection pump provides for fast priming of the hydraulic system after extended compressor shutdowns. On the compression stroke of the main piston, the hydraulic check valve isolates the hydraulic system from the automatic injection pump so that an elevated pressure can be generated in the system against the hydraulic overpump valve.    


The Diaphragm Sealless Compressor System

  1. Check valves: Ball, poppet, or plate check valves are specified to match operating conditions and process gas. Valves are readily accessible for inspection, repair, or replacement, and can be removed without disassembly of the compressor head.
  2. Hydraulic inlet check valve: Contains the injected hydraulic fluid within the head assembly. Valve body is stainless steel. Ball is tungsten carbide.
  3. Hydraulic pistons: For design pressures to 3000 psi (200 bar), pistons are sealed with high-quality cast iron or filled-plastic piston rings in a hardened, honed sleeve. For higher pressures a packless, ringless piston is lap-fitted to a hardened, honed sleeve; the hydrodynamic film between the two provides the lubrication and the pressure seal.
  4. Hydraulic overpump valves: Controls the pressure of the hydraulic system. The combined movement of stem, ball, and spring determines the pressure range of the valve. Valve body is carbon steel. Seat and stem are hardened tool steel.
  5. Overpump sight glass: Provides visual indication that hydraulic fluid is being forced through the overpump valve and that the hydraulic system is functioning properly.
  6. Hydraulic injection pump: Driven by the crankshaft, the pump injects fluid into the hydraulic system. Pump plunger is spring-loaded and is matched to the sleeve. Plungers are cast iron; sleeves are alloy steel.
  7. Frames: All Sundyne PPI diaphragm sealless compressors are based on rugged cast-iron crankcase frames with fully gasketed access covers.
  8. Piston rods: High-strength alloy steel piston rods are locked into a one-piece crosshead.
  9. Crossheads: Compressors driven by 20 hp or larger motors have precision-fitted, box-type crossheads made from ductile iron or aluminum.
  10. Crosshead pin: Straight-fit floating design made from high-strength hardened steel. On low-boost compressors, anti-friction bearings are fitted to the crosshead pin area to reduce wear.
  11. Connecting rods: I-beam rods of die-forged steel or aluminum deliver maximum strength at minimum weight.
  12. Main and crankpin bearings: Full floating bearings with a high load capacity. Lubricated by a thin film distributed evenly around inside and outside surfaces for minimal wear. All bearings selected for extreme radial loading and optimum life on belt-driven frames.
  13. Crankshafts: Made from high-strength alloy steel with ground and polished bearing journals; crankshafts on 2000 Series and larger models are rifle drilled for lubrication.

Diaphragm Sealless Compressor Diagram 1




Diaphragm Sealless Compressor Diagram 2