Liquid Filter Bag Installation & Startup Guide

Installing a liquid filter bag is not only a matter of placing a bag in a vessel. The housing model, restrainer basket, bag size, ring or collar, seal material, flow direction and operating procedure must work together. This guide provides a practical pre-start checklist, but the exact opening, closing, venting and return-to-service steps must come from the housing manufacturer and the plant’s approved procedure.

1. Identify the Housing and Approved Procedure

Record the housing manufacturer, model, serial or drawing reference, bag quantity and flow direction before work begins. Obtain the current operating manual for that exact housing. Do not borrow torque values, valve sequences or pressure limits from a different vessel.

If the housing or bag specification is still being selected, review the bag filter housing selection guide first.

2. Shut Down, Isolate and Confirm Zero Pressure

Follow the site’s lockout, isolation, draining and personal-protection procedure. Confirm that the housing is isolated from every pressure source and that pressure has been safely released before opening. Treat hot, corrosive, toxic, flammable or otherwise hazardous liquid as a separate risk requiring the site’s approved controls.

Never assume that a gauge reading alone proves the vessel is safe to open. Use the verification method required by the plant and the housing manufacturer.

3. Confirm the Bag, Basket, Ring and Seal Match

• Confirm the bag size and length against the housing and basket.
• Confirm the ring or molded collar style against the basket seat and hold-down arrangement.
• Confirm the filter material, micron rating and seal material against the process liquid and temperature.
• Confirm that the restrainer basket and any fixing ring or hold-down device belong to the housing configuration.

Size #1 and #2 are common trade references, but a trade-size label does not replace a housing fit check. See liquid filter bag size #1 vs #2 and the detailed ring and collar guide.

4. Inspect the Basket and Sealing Area

Before installing the bag, inspect the basket, basket seat, sealing surface, gasket or O-ring, hold-down components and housing interior. Remove residue from the seating area using a process-compatible method. Do not continue with a basket that is visibly deformed, damaged or capable of abrading the bag. Replace damaged seals and other parts according to the housing manual.

5. Seat the Bag Without Folds or Unsupported Areas

1. Install the correct restrainer basket in its intended position.
2. Lower the bag into the basket without dragging the media across sharp or dirty surfaces.
3. Open the bag against the basket so the media is supported along its length.
4. Position the bag ring or collar evenly on the housing-specific basket edge or retainer seat.
5. Install the correct fixing ring, bayonet, hold-down or cover-actuated device only as specified by the manufacturer.

Before the cover is closed, check that the bag is not twisted, doubled over, pinched in the sealing path or left unsupported. The ring or collar should sit evenly rather than being forced into place.

6. Complete the Pre-Closing Check

Confirm that tools and loose objects have been removed, the sealing area is clean, the gasket is correctly positioned and the bag cannot be caught by the cover. Close and secure the vessel using the exact manufacturer procedure. Do not apply a universal torque value or copy a closure sequence from another housing.

7. Return the Housing to Service Gradually

Use the OEM manual and plant procedure for venting, valve order and return to service. Manufacturer manuals commonly require a controlled, gradual introduction of flow and management of trapped air, but the details vary by housing and process. Protect personnel from any vented or discharged liquid.

Do not use a generic startup pressure, flow percentage, maximum flow or differential-pressure limit unless it is documented for the exact housing, basket, bag and duty.

8. Observe the Initial Operating Period

During the initial return to service, observe the housing and process instruments for external leakage, abnormal pressure behavior, unexpected vibration, unstable flow or evidence that the bag has moved from its seat. If an abnormal condition appears, stop and investigate under the approved procedure rather than tightening a pressurized closure or forcing additional flow.

For symptom-specific checks, use the guides on seal leakage, bag collapse or floating, and differential-pressure information for an RFQ.

Installation and Startup Checklist

• Exact housing model and current OEM procedure available
• Housing isolated, drained as required and verified depressurized
• Bag size, media, micron rating, ring/collar and seal confirmed
• Correct basket installed and inspected
• Sealing surfaces and gasket clean and undamaged
• Bag fully opened against the basket and evenly seated
• Bag clear of the closure and sealing path
• Housing closed using the model-specific procedure
• Return to service gradual and venting controlled as specified
• Initial leakage, pressure, vibration and flow observations recorded

Information to Send for Technical Review or an RFQ

Provide the housing manufacturer and model, photos of the open housing and basket, bag size, ring or collar style, gasket material, filter media and micron rating, process liquid, operating temperature, normal flow, available inlet and outlet pressure information, quantity and the problem being investigated. Photos of the basket seat, sealing area and the removed bag can reduce fit and diagnosis errors.

Frequently Asked Questions

Can a liquid filter bag operate without a basket?

A standard bag needs the housing’s restrainer basket to support it against operating differential pressure. Use only the configuration approved for the specific housing.

Should the bag ring sit above or inside the basket?

The required position depends on the basket, retainer plate, ring or collar and hold-down design. Confirm it from the housing drawing or manual rather than assuming a universal position.

Why must the bag be fully opened against the basket?

Full support helps prevent unsupported media, poor seating and movement during startup. A folded or twisted bag can also interfere with the sealing path.

What differential pressure is safe for startup?

There is no universal value for every housing and bag. Use the documented limit for the exact vessel, basket, bag and operating duty.

What should be checked if leakage appears after startup?

Stop under the approved procedure and check the housing seal, bag ring or collar seating, basket position, sealing surfaces, closure condition and component compatibility. Do not tighten a pressurized housing to overcome a suspected seal problem.