Installation and Maintenance of Gaseous Fuel Filters{1261, 1262} Caterpillar

Introduction

Filter groups are now available for the above Gas Engines. This Special Instruction provides the necessary information to install and maintain this filter system.

Filter systems are recommended to increase the service life of gas engines. Gas lines contain varying amounts of scale and rust which can cause regulator or carburetor malfunction. Fuel directly from a gas well may have abrasives or liquids entrained in the gas as well as other contaminants such as sulfur.

The filter groups listed are for engine applications using dry, high inlet pressure, natural gas. Consult the factory for proper filter sizing using other types of gas and different inlet pressures.

Filter elements should be checked when Delta P reaches 34.45 kPa (5 psi).

Use a 68.9 kPa (10 psi) Delta P gauge connected upstream and downstream of the filter housing as specified in the installation instruction.

The standard arrangement will be for particulate filtration (top cap with white lettering). Special top cap with yellow lettering is available for filtration (coalescing) of liquids.

NOTE: Both caps are included in the filter group from the supplier.

Installation

Guidelines

All plumbing is to be installed in accordance with local, state, and national codes.

Clean all piping during filter installation to eliminate filter contamination and to increase service life.

Observe flow direction when installing filter system. Gas flow direction is specified by arrow indication on filter group top cap.

Mount filters vertically and allow adequate room to remove the filter housing for element replacement.

Do not use pipe sizes smaller than specified.

Vent piping for engines located indoors to be vented outside and in conformance with local, state, and national codes.

Procedure

(A) Main Fuel Shutoff Valve. (B) Union. (C) Filter. (D) 1/2 inch NPT Vent Valve. (E) 68.9 kPa (10 psi) Delta P Gauge. (F) Dimension = Five Pipe Diameters. (G) Dimension = 10 Pipe Diameters. (H) Gas Pressure Regulator. (J) S.I. Engine.

1. Check installation to determine if main fuel shutoff valve is installed. Install main shutoff valve if necessary, upstream of pressure regulator and upstream of filter location.

NOTE: Use the shutoff valve to shut down the engine. If the ignition is shorted to shut down the engine, gas is still trapped in the line and will eventually enter the exhaust system.

2. Mount filter housing as close to engine as possible and high enough for easy filter housing removal.

Pipe unions can be installed to allow filter housing to swing outward, but should not be located within the pressure measuring points.

NOTE: This is necessary to ease changing filter elements.

3. Determine the pipe size for your filter group from the chart above.

NOTE: All vent piping to be 1/2 inch NPT.

4. Determine pressure drop gauge point locations. The upstream location should be a minimum of five pipe diameters from the filter and the downstream location should be a minimum of 10 pipe diameters.

5. Install a 68.90 kPa (10 psi) gauge between the pressure drop gauge point locations (across the filter system) to be used as a means of monitoring the filter.

6. Install 1/2 inch NPT valve and pipe for blow down capability. This line should be vented outside for indoor engine installations. A union should be installed between the filter housing and blow down valve for easier housing removal.

Maintenance

Use the differential pressure gauge indication as the basis for inspecting and replacing the filter element.

When differential pressure reaches 34.45 kPa (5 psi), the filter element should be inspected and possibly replaced.

Filter Replacement

1. Shut off the main gas supply to the engine.

2. Open blow down valve to remove any pressure remaining in the filter housing.

3. Disconnect blow down piping and unscrew the filter bowl.

4. Remove the filter element.

5. Install a new O-ring and filter element.

For 4P-4716 Filter Groups, install a new O-ring (supplied with replacement filter) and screw new element into housing.

For 4P-4717 and 4P-4718 Filter Groups, install a new O-ring and filter element. Secure element with O-ring and rod nut. Tighten rod nut to 9.5 N·m (85 lb in).

6. Check condition of the bowl seal O-ring. Replace if necessary. Clean the bowl and bowl threads.

7. Install the bowl by screwing the bowl into the housing being careful not to damage the bowl seal O-ring.

8. Install the blow down piping, and turn ON the gas valve to pressurize the filter housing.

9. Check the filter for leaks. If leaking is evident, shut off the main gas valve, open the blow down valve to release the pressure in the filter bowl, remove the blow down piping and filter bowl. Check the bowl O-ring seal, replace if necessary. Assemble the filter and check it again for leaking.