The Graco Dura-Flo™ 750 Pumps are carbon steel displacement pumps designed for professional use with severe-duty rods and cylinders. This manual, 308-417 Rev. C, supersedes Rev. B and provides instructions and parts lists for various models, including King™ and Bulldog® pumps, with different ratios and configurations.
Function Description:
The Dura-Flo™ 750 Pumps are designed to transfer fluids under high pressure. They operate using an air motor that drives a displacement pump, which in turn moves the fluid. The pumps are suitable for applications requiring high fluid working pressures, with King™ models reaching up to 42.2 MPa (6120 psi) and Bulldog® models up to 22.8 MPa (3300 psi). The system is designed to be grounded to prevent fire and explosion hazards, and proper ventilation is required when operating with flammable fluids or solvents.
Important Technical Specifications:
- Maximum Fluid Working Pressure:
- King™ Pumps (236-459, 237-364): 42.2 MPa, 422 bar (6120 psi)
- Bulldog® Pumps (237-366, 237-370, 237-582): 22.8 MPa, 228 bar (3300 psi)
- Maximum Air Input Pressure:
- King™ Pumps: 0.63 MPa, 6.3 bar (90 psi)
- Bulldog® Pumps: 0.7 MPa, 7 bar (100 psi)
- Ratio:
- King™ Pumps: 68:1
- Bulldog® Pumps: 33:1
- Pump Cycles per 3.8 Liters (1 Gallon): 21
- Fluid Flow at 60 Cycles per Minute: 11.0 liters/min (2.9 gpm)
- Air Motor Piston Effective Area:
- King™ Pumps: 506 cm² (78.5 in.²)
- Bulldog® Pumps: 248 cm² (38 in.²)
- Stroke Length: 120 mm (4.75 in.)
- Displacement Pump Effective Area: 7.5 cm² (1.16 in.²)
- Maximum Operating Temperature: 82°C (180°F)
- Air Inlet Size: 3/4 npsm(f)
- Fluid Inlet Size: 1-1/2" npt(f)
- Fluid Outlet Size: 3/4 npt(f)
- Pump Weight:
- King™ Pumps: approx. 48 kg (105 lb)
- Bulldog® Pumps: approx. 41 kg (90 lb)
- Displacement Pump Weight: approx. 15 kg (34 lb)
- Wetted Parts: Carbon Steel; Alloy Steel; 304, 440 and 17-4 PH Grades of Stainless Steel; Zinc and Nickel Plating; Ductile Iron; Tungsten Carbide; PTFE; Leather; Titanium Carbide (for King™ Pumps only).
- Sound Pressure Levels (dBa) at 15 cycles per minute (measured at 1 meter from unit):
- King™: 78.8 dB(A) at 0.28 MPa (40 psi) to 90.5 dB(A) at 0.63 MPa (90 psi)
- Reduced Icing Quiet King™: 77.9 dB(A) at 0.28 MPa (40 psi) to 87.5 dB(A) at 0.63 MPa (90 psi)
- Bulldog®: 82.4 dB(A) at 0.28 MPa (40 psi) to 90.0 dB(A) at 0.7 MPa (100 psi)
- Reduced Icing Quiet Bulldog®: 81.5 dB(A) at 0.28 MPa (40 psi) to 85.8 dB(A) at 0.7 MPa (100 psi)
- Sound Power Levels (dBa) at 15 cycles per minute (tested in accordance with ISO 9614–2):
- King™: 86.5 dB(A) at 0.28 MPa (40 psi) to 97.7 dB(A) at 0.63 MPa (90 psi)
- Reduced Icing Quiet King™: 85.2 dB(A) at 0.28 MPa (40 psi) to 95.2 dB(A) at 0.63 MPa (90 psi)
- Bulldog®: 91.6 dB(A) at 0.28 MPa (40 psi) to 98.1 dB(A) at 0.7 MPa (100 psi)
- Reduced Icing Quiet Bulldog®: 90.2 dB(A) at 0.28 MPa (40 psi) to 93.3 dB(A) at 0.7 MPa (100 psi)
Usage Features:
- Grounding: The pump system, including air and fluid hoses, air compressor, spray gun, fluid supply container, object being sprayed, and solvent pails, must be properly grounded to prevent fire and explosion hazards. Electrically conductive hoses are required.
- Pressure Relief Procedure: A critical safety procedure that must be followed whenever instructed to relieve pressure, stop spraying, clean, check, or service the equipment, or install/clean spray tips. This involves locking the gun trigger safety, shutting off air supply, closing the bleed-type master air valve, unlocking the trigger safety, triggering the gun into a grounded metal pail, re-locking the trigger safety, and opening the drain valve.
- Starting and Adjusting: The pump is primed by connecting the suction kit, closing the air regulator, opening the bleed-type master air valve, holding the gun trigger open into a grounded pail, and slowly opening the regulator until the pump starts and all air is purged. The air regulator controls pump speed and fluid pressure, and the lowest effective air pressure should always be used to minimize wear.
- Flushing: The pump should be flushed before first use to remove lightweight oil used for protection. It must also be flushed before the fluid dries on the displacement rod, using a fluid compatible with the pumped fluid and wetted parts. For water-base fluids, flush with water first, then with a rust inhibitor.
- Packing Nut/Wet-Cup: The packing nut should be filled 1/3 full with Graco Throat Seal Liquid (TSL) or a compatible solvent before starting. If leakage occurs, the packing nut should be torqued to 61-75 N•m (45–55 ft-lb) using the supplied wrench.
- System Accessories: The manual provides guidance on selecting and installing system components such as air line filters, lubricators, bleed-type master air valves, pump air regulators, air manifolds, fluid filters, and fluid drain valves. Electrically conductive hoses with spring guards are recommended for fluid lines.
Maintenance Features:
- Daily Checks: Equipment should be checked daily for worn or damaged parts, and repairs or replacements should be made immediately. Hoses, tubes, and couplings should be checked daily, and worn or damaged parts replaced.
- Troubleshooting Chart: A comprehensive chart helps diagnose common problems such as pump failure to operate, low output, or erratic speed, providing potential causes and solutions (e.g., clearing air lines, checking valves, replacing packings, refilling fluid supply).
- Displacement Pump Service: Detailed instructions are provided for disassembling, inspecting, and reassembling the displacement pump. This includes removing the intake valve, intake housing, cylinder, and piston assembly.
- Packing Repair Kits: Packing Repair Kits are available, and using all new parts from the kit is recommended for best results. The manual also describes how to convert the pump to different packing materials (e.g., Leather, PTFE, UHMWPE/Leather, UHMWPE/PTFE).
- Torque Specifications: Specific torque values are provided for critical components during reassembly, such as the piston ball housing to the rod (258-285 N•m), coupling nut to motor shaft (195–210 N•m), tie rod nuts (68-81 N•m), intake housing to cylinder (325-353 N•m), intake valve (190–217 N•m), and packing nut (61-75 N•m).
- Lubrication: Lubrication is required for piston packings, cylinder threads, and seals during reassembly.
- Air Motor Service: For servicing the air motor, users are directed to refer to the separate motor manual supplied with the pump.
- Warning Labels: Replacement Danger and Warning labels, tags, and cards are available at no cost to ensure safety information remains visible.
Warranty:
Graco offers a twelve-month warranty on equipment manufactured by Graco, covering defects in material and workmanship. This warranty is conditional on proper installation, operation, and maintenance. A special extended warranty of 36 months is offered for Dura-Flo™ displacement pump lowers. The warranty does not cover general wear and tear, or damage due to faulty installation, misuse, or non-Graco parts.
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