Contact Go2Filter / FiltEdge
Email: info@filtedge.com
Phone: +1 949-682-0025
Address: 15375 Barranca Parkway, Suite B-204, Irvine, CA 92618
RFQ Support
Please share product type, size, material, micron rating, quantity, application, and operating conditions.
Differential pressure can help a buyer explain how a liquid bag filter is behaving, but one number is rarely enough for a useful quotation review. A supplier needs to know where the readings came from, the operating conditions at the time, what changed in the process, and which bag and housing were installed. Without that context, a rising or unstable reading can be misread as a filter-bag problem when the cause may involve flow, viscosity, solids loading, valves, instrumentation, bag seating, the support basket, or another part of the system.
This guide is a practical record-preparation checklist. It does not set a universal change-out pressure or a maximum allowable differential pressure. Those limits must come from the documentation for the actual housing, filter bag, pressure instrument, process equipment, and the site’s approved operating procedure.
Differential pressure is the difference between pressure at two defined points. For filter monitoring, the points are normally associated with the upstream and downstream sides of the filter housing. Record the upstream pressure, downstream pressure, and calculated difference rather than reporting only a single number. Include the unit exactly as shown by the instrument, such as the site’s chosen pressure unit, and do not convert it unless the original reading is also retained.
The location and condition of each measuring point matter. Note whether the system uses two separate gauges, one differential-pressure gauge, a transmitter, or another arrangement. Record instrument identification, range, calibration or verification status if known, and whether impulse lines, isolation valves, or remote seals are part of the setup. If a reading appears inconsistent with process behavior, the site should verify the instrument and its connections under its normal maintenance procedure before treating the reading as proof of filter condition.
After a correctly selected bag is installed and the system reaches stable operation, record a baseline. The record should include the date and time, bag identification, upstream and downstream readings, differential pressure, flow rate, liquid temperature, pump or line condition, and any relevant valve positions. If the process runs in batches or at several flow settings, identify the specific operating point.
A baseline is most useful when later readings are taken under comparable conditions. A reading at startup should not automatically be compared with one taken at a different flow, temperature, batch stage, or solids concentration. Keep the original observations as a time series: for example, after startup, at a defined production point, and before the bag is inspected or changed. The purpose is to show the trend and the surrounding conditions, not to force every system into one universal curve.
Differential pressure may change when more solids collect in the bag, but solids loading is only one variable. Record any change in production rate, flow, liquid temperature, viscosity, solids concentration, particle character, batch formulation, upstream treatment, or recirculation. A colder or more viscous liquid may produce a different pressure relationship from the same liquid at another condition. A change in feed solids or an upstream upset can also change the loading pattern.
Include operating events on the timeline. Note pump starts or speed changes, valve adjustments, line changeovers, cleaning, flushing, pre-filter changes, and any opening of a bypass route. If the pressure trend changed after maintenance or a bag replacement, identify the exact time. This allows the supplier to compare the reading with a physical event instead of assuming that the filter medium alone caused it.
The filter bag operates as part of an assembly. Record the housing manufacturer and model if available, the number of bags, connection size, flow direction, support-basket condition, and any hold-down or restraining parts. Photograph the bag top, ring or collar, basket, seating surface, cover seal, and the bag after removal when site procedures permit.
Confirm that the installed bag size and top construction match the housing arrangement. A seating, ring, collar, basket, or seal issue belongs to a different diagnostic path from normal media loading. Likewise, an unexpected low, high, or unstable reading does not by itself prove bypass, leakage, collapse, or a defective bag. Use the related guides for a focused review of ring and collar fit, seal leakage or bypass symptoms, and bag collapse or floating.
The table below is a compact RFQ preparation record. Send what is available; unknown fields can be marked for supplier review.
| Record group | Information to provide | Why it helps review |
|---|---|---|
| Pressure readings | Upstream pressure, downstream pressure, differential pressure, units, timestamps and trend | Shows what was measured and when |
| Measurement setup | Instrument type, ID/range, tap locations and verification status if known | Helps separate process behavior from a measurement issue |
| Operating point | Normal and observed flow, temperature, viscosity if known, pump state and valve positions | Allows comparison under defined conditions |
| Contaminant load | Solids type, approximate loading or process observation, particle information and batch changes | Provides context for loading and restriction |
| Current bag | Size, diameter and length, material, construction, micron rating and nominal/absolute basis if known | Identifies the element being replaced or reviewed |
| Top and housing fit | Ring/collar style, seam, housing model, basket, seals and flow direction | Supports compatibility and seating review |
| Service history | Install date, baseline, pressure trend, service time, cleaning or change-out event | Shows the sequence rather than one isolated reading |
| Evidence | Photos of bag, label, ring/collar, basket and housing; drawings or previous part number | Reduces ambiguity in replacement matching |
| Commercial need | Required quantity, destination and whether this is replacement stock or a new application | Lets the sales team prepare the correct follow-up |
For material and rating context, review the micron rating guide. For a new or replacement vessel, use the bag filter housing selection guide. The Liquid Filtration Guides hub provides the complete technical topic path.
Use observable language. A useful note might say that the differential-pressure reading increased over a stated period while flow, temperature, and formulation were recorded, or that the reading changed after a bag replacement or valve adjustment. Avoid statements such as “the bag is defective” unless inspection and evidence support that conclusion. Also avoid applying a threshold taken from another filter, housing, or supplier document to the current system.
If the site’s approved limit has been reached, follow the equipment manufacturer’s and site’s isolation, depressurization, draining, opening, and personal-protection procedures. This article is not an operating or safety procedure. Do not open a pressurized housing to obtain photos or measurements.
No. Media loading can contribute, but flow, temperature, viscosity, solids changes, valve position, piping, instrumentation, seating, basket condition, and other system factors may affect the observation. Record the surrounding conditions before assigning a cause.
Use the limit or decision rule approved for the actual housing, bag, instrument, process, and site. This guide does not provide a universal numeric threshold.
Send the upstream and downstream readings, the calculated difference, units, timestamps, operating conditions, instrument arrangement, and trend. A single number without context is difficult to evaluate.
They help define whether readings were taken under comparable conditions. Changes in operating conditions can change the observed pressure relationship, so they should be documented with the trend.
When site procedures allow, provide the full used and new bag, label or markings, diameter and length, ring or collar from several angles, basket, seating area, housing nameplate, and any drawing or previous part reference.
Combine the pressure record, operating conditions, bag specification, housing information, quantity, photos, and drawings into one request. If some details are unknown, identify them clearly so the supplier can focus the follow-up. To send the available information for product review, request a filtration product quote. The quotation team can then review the replacement or application requirements without treating an isolated differential-pressure reading as a complete diagnosis.