Graco 332096A User Manual

Instructions

332096A

Dispense Valve

Important Safety Instructions

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Dispensit 792-20

MODEL 792-20

DISPENSE VALVE

OPERATING & MAINTENANCE MANUAL

General Information ...................................................................................3

Safety Information ......................................................................................3

Illustration References ...............................................................................3

General Accessories ..................................................................................3

Description Of Operation ...........................................................................4

Setup Procedures .......................................................................................4

Mounting Dispense Valve ..........................................................................4

Air Controller ..............................................................................................4

Operating Procedures ................................................................................5

Dry System Checkout ...............................................................................5

Material Loading .......................................................................................5

Remote Mounted Material Supply .........................................................5

Wet System Checkout ..............................................................................6

Periodic Maintenance .................................................................................6

Material Hose Renewal ...........................................................................6

Material Hose Replacement ....................................................................7

Disassembly ............................................................................................8

Model 792-20 General Illustration ............................................................9

Assembly .................................................................................................10

Troubleshooting .........................................................................................11

Model 792-20 Recommended Spare Parts................................................12

General Guidelines for O-rings and U-cup Seals .....................................13

Warranty ......................................................................................................14

GENERAL INFORMATION

The Model 792-20 Dispense Valve is designed for applications that require ON/OFF dispensing of beads and/or dots. It has dispensing capability for material viscosities ranging from water-type material to high viscosity epoxies and metal filled pastes. This valve also has a fail-safe design to prevent material dumping in case of a power failure. All wetted parts are disposable for easy maintenance and cleaning. The 792-20 ships complete with the following:

Model 792-20 Dispense Valve One 3 foot (.9 m) section of pneumatic air line One material hose (type as ordered) Seal Kit Operating and Maintenance Manual

SAFETY INFORMATION

This product should be used only by employees who have been given appropriate training and safety warnings as set forth in this manual. Read completely before operating.

Warning: Do not exceed 100 psi (6.9 bar) pressure on the operating system or 60 psi (4.1 bar) material supply pressure. Higher pressures are not required and may cause a serious hazard.

Toxicity and flammability hazards depend upon the product being dispensed by this unit, and the user should take appropriate safety precautions as indicated on the MSDS of the product.

Always wear safety glasses.

ILLUSTRATION REFERENCES

Throughout this manual you will find references by illustration item number to the illustrations in the manual. The references are indicated by parentheses around a number such as: (7). Illustrations represent typical valve configurations. The drawings for your exact model are inserted at the back of the manual and include the part numbers for ordering replacement parts.

GENERAL ACCESSORIES

Graco | Liquid Control offers a full line of standard and custom accessories for your dispensing needs including:

Valve Controllers Syringe Feed Systems Cartridge Retainers and Pressure Reservoirs Transfer Pump Feed Systems for 1, 5 and 55 gallon containers Mounting Bases and Brackets

Consult your Dispensit dealer or the factory for details.

DESCRIPTION OF OPERATION

1. The normal ready state of the system is as follows: The syringe or remote reservoir contains the dispensable material. The system has been purged, filling the material hose and needle with material. The Pinch-off Piston (11) is not pressurized, but is held back by the Springs (10) closing the

Material Hose (16) and holding back the dispensable material.

2. The dispense cycle begins when the controller is activated.

3. The Pinch-off Piston (11) moves forward to release the Material Hose (16) allowing material to flow.

4. To complete the dispense cycle, the Pinch-off Piston (11) is pushed back by the Springs (10), sealing

the Material Hose (16) to prevent material drip. The system is again in the normal ready state.

SETUP PROCEDURES

MOUNTING DISPENSE VALVE

For optimum operation, the Model 792-20 Dispense Valve must be mounted on a 1/2 inch (12.7 mm) support rod post or frame. When mounting, affix the valve firmly in place by tightening the socket head cap screw with a 5/32 inch Allen wrench. Depending on the application, the valve may be tilted to a maximum of 600 from the vertical.

AIR CONTROLLER

Operation of the Model 792-20 Dispense Valve requires a controller that can provide the following:

A minimum of 0.5 SCFM (2.3 cm3) of dry, unlubricated air at a minimum pressure of 4.8 bar (70 psi)

and a maximum of 6.9 bar (100 psi). Time delay capability to allow the valve to cycle. Independent air pressure regulators for material reservoir and valve operation. “Purge capability” which is the ability for the operator to pass or not pass air to the Pinch-off Piston

(11) on the dispense valve. For semiautomatic or automatic applications, a foot switch or other control to cycle the valve. Connection for .16” ID x .25” OD(6.35mm) pressure tubing for use between the dispense valve and

controller. Connection for .16” ID x .25” OD(6.35mm) pressure tubing for use between the controller and syringe.

NOTE: The material supply must be regulated to a maximum of 60 psi (4.1 bar).

OPERATING PROCEDURES

DRY SYSTEM CHECKOUT

This is an initial checkout to determine if the setup has been properly completed. Conduct the dry system checkout without any material in the system.

1. Attach the color-coded pneumatic pressure line from the air inlet fitting on the valve to the color-coded cycle air outlet on the air supply controller.

2. Turn on the electric and air supply.

3. Set the air pressure to 70 psi (4.8 bar) on the system pressure gauge.

4. In the normal rest position the Pinch-off Piston (11) is held back by the Springs (10), sealing the Material Hose (18).

5. Momentarily press the dispense valve cycling control switch. The Pinch-off Piston (11) is pressurized to release the Material Hose (18). The controller air solenoid valve should cycle and cause a slight fluctuation in the system pressure gauge. When this happens, the system is correctly installed.

MATERIAL LOADING

REMOTE MOUNTED MATERIAL SUPPLY

Connect the Material Hose either directly to the material supply reservoir or to material supply tubing that connects to the material supply reservoir. When using a remote reservoir, the material supply tubing and fittings must be compatible with the material being dispensed and be capable of withstanding the dispensing pressure.

Warning: Do not exceed 100 psi (6.9 bar) pressure on the operating system or 60 psi (4.1 bar) material supply pressure. Higher pressures are not required and may cause a serious hazard.

WARNING: Do not apply either operating or reservoir air pressure to the product unless all screws are in place and properly tightened, and the receiver cap and/or reservoir lid is properly in place and tightened. All air connections should be fastened securely.

WET SYSTEM CHECKOUT

Using the purge cycle on the air supply controller, run the material through the dispense line until a smooth material flow is observed through the dispensing outlet.

After the purge cycle has been completed, set the air supply controller to the manual cycle mode and cycle the Dispense Valve several times.

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