LD Low Pressure Diaphragm
 Key
Features
- Simple Design
- Easy to Maintain
- Intrinsic Safety of Pneumatic Operation
- Stroke Length and Stroke Rate Adjustment
- High Flow Turndown
- Corrosion Resistant Construction
- All 316 SS or TFE Wetted Parts
- Ease of Installation
- Recommended for discharge pressures below 120 PSI
STANDARD MATERIALS
- Wetted Parts - 316SS or TFE
- Pneumatic Section - 316SS
- Diaphragm - TFE (Teflon)
- Controller - 316SS
- Relays - 316SS
DESIGN IMPROVEMENTS
- Higher Flow Rates than PD Series pump models
- All TFE diaphragms for all pump sizes
- TFE-coated o-rings in contact with process fluid
- Viton® o-rings in contact with air/gas supply
- Stroke Adjuster locks in place with a simple thumbscrew
- Stroke Adjuster scale easier to read and set than previous diaphragm
pump models
- Check Valves for 316SS models have TFE soft seats with 316SS balls.
(LD200 & 400)
- Check Valves for TFE models have TFE soft seats with Zirconium balls.
(LD200 & 400)
- Check Valves on LD100 models are Kynar with Kynar soft seats and
Zirconium or Ruby Sapphire balls
 Operation 
POWER STROKE
As the air or gas enters the MOTOR CHAMBER from the controller, the
DIAPHRAGM is driven into the fluid cavity of the FACEPLATE, displacing
the fluid in the FACEPLATE and extending the RETURN SPRING. As the
fluid is displaced, the rise in pressure closes the SUCTION CHECK
VALVE and opens the DISCHARGE CHECK VALVE. A precise amount of fluid
corresponding to the stroke of the DIAPHRAGM is discharged.
SUCTION STROKE
When the air or gas pressure is exhausted from the MOTOR CHAMBER, the
RETURN SPRING assists the DIAPHRAGM in returning to its static position.The
retraction of the DIAPHRAGM reduces the pressure in the fluid cavity,
thus closing the DISCHARGE CHECK VALVE and opening the SUCTION CHECK
VALVE. The fluid cavity is again filled, preparing the pump for another
power stroke.
 Performance
VISCOSITY:
Maximum recommended viscosity 1280 CP (Centipoise) or 6000 SSU (Saybolt
Seconds Universal).
STATIC SUCTION LIFT: (Inches of Water)
The maximum volume of the pumps is reduced under a suction lift condition.
The maximum suction lift capability for each pump is 60 inches. (with
the footvalve on the tank end of a rigid suction line.)
OPERATING TEMPERATURE:
The recommended operating temperature of the pumps with the corresponding
faceplate and standard diaphragm material is as follows:
- 316 SS: -15°F (-26°C) to 185°F(85°C)
- TFE: -15°F (-26°C) to 185°F (85°C)
For temperatures beyond these limits, please consult the factory.
MAX FLOW RATE AT 60" LIFT WITH FOOT VALVE:
- LD100-TFE-TFE 0.7GPH (2.6LPH)
- LD200-TFE-TFE 9.7GPH (36.7LPH)
- LD400-TFE-TFE 45.0GPH (170.3LPH)
PERFORMANCE GRAPHS:
 Dimensions
& Specifications
PART NUMBERING SYSTEM
 Literature
Downloads
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