Filter replacement procedures and kit numbers for the CPi-Plus & CPx-Plus Series are identical to those for the standard CPi & CPx Series. The only difference is how the filter alarm is reset: the Plus Series uses the touchscreen rather than a physical button hold. For CPx-Plus models, the correct filter kit also depends on when the unit was built.
CPi-Plus Models — Filter Kit FRP-001
CPi-Plus models (2CPi-Plus, 4CPi-Plus) include three filters: an air intake pre-filter on the compressor, a 5-micron particulate filter, and a 0.1-micron coalescing filter. All three must be replaced annually or every 1,000 run hours, whichever comes first.
Air Intake Pre-Filter
- Stop the generator via the touchscreen and power down the unit. Remove the front cabinet cover.
- Locate the pre-filter on the air intake of the integral compressor.
- Twist the pre-compressor filter cap clockwise to remove it.
- Pull out the old element and wipe the filter bowl clean with a dry cloth.
- Install the new element and replace the cap.
Particulate Filter
- Confirm zero pressure on the filter bowl (the gauge after the filter housing reads 0 PSIG).
- Unscrew the filter bowl counterclockwise and remove it.
- Rinse the bowl with warm water; dry with a clean cloth.
- Replace the old O-rings with those provided in the FRP-001 kit.
- Remove the old particulate element using a Phillips-head screwdriver and install the new element.
- Reinstall the bowl into the filter housing.
Coalescing Filter
- With the bowl removed (same procedure as particulate filter above), twist the coalescing element counterclockwise to remove.
- Install the new element in reverse order.
- Reinstall the cleaned bowl with fresh O-rings.
After Replacing CPi-Plus Filters
- Replace the front cabinet cover.
- Power on the unit. The compressor will start and begin producing nitrogen.
- Check all filter bowl connections for leaks.
- Reset the filter alarm using one of the two methods below.
Filter alarm reset — Method 1 (touchscreen): Navigate to the Alarms button → Filter Info. Press the green button next to the filter element that was replaced. The status will update to Good and the filter calendar will reset.
Filter alarm reset — Method 2 (filter reset button on electrical panel): Press and hold the dedicated filter reset button on the electrical panel until an audible beep confirms the reset.
CPx-Plus Models — Identifying Your Filter Generation
CPx-Plus models (2CPx-Plus, 4CPx-Plus) were produced with two different filter assemblies depending on manufacture date. Before ordering a replacement kit, identify which generation is installed by checking the color of the filter housings inside the cabinet.
| Housing Color | Manufacturer | Replacement Kit | Unit Age |
|---|---|---|---|
| Black | Wilkerson | FRP-1-1 | Older units |
| Off-white | ASCO | FRP-019 | Newer units |
CPx-Plus Models — Wilkerson Filters (Black) — Kit FRP-1-1
Units with black Wilkerson filter housings use kit FRP-1-1. The three filters are replaced on a staggered schedule based on contamination loading.
| Filter | Rating | Replacement Interval |
|---|---|---|
| Particulate | 5 micron | Every 3 months (4× per year) |
| Coalescing | 0.01 micron | Every 6 months (2× per year) |
| Absorber | 0.003 micron / activated carbon | Every 12 months (1× per year) |
CPx-Plus Models — ASCO Filters (Off-White) — Kit FRP-019
Units with off-white ASCO filter housings use kit FRP-019. All three filter elements are replaced on the same 6-month schedule. The kit includes 2 of each element, covering a full year of service in a single order.
| Filter | Rating | Replacement Interval |
|---|---|---|
| Particulate | 5 micron | Every 6 months (2× per year) |
| Coalescing | 0.01 micron | Every 6 months (2× per year) |
| Absorber | 0.003 micron / activated carbon | Every 6 months (2× per year) |
CPx-Plus Filter Replacement Procedure
The replacement procedure is the same for both filter generations. The only difference is the bowl removal method in step 4 — note which applies to your unit.
- Stop the generator via the touchscreen and valve off the incoming air supply.
- Open the service valve after the filters to relieve pressure. Confirm 0 PSIG on the air supply gauge.
- Disconnect condensate drain tubes from the bottom of the filter bowls.
- Remove each filter bowl:
- Wilkerson (black housings — FRP-1-1): Push the bowl latch down and rotate counterclockwise while pulling down. If the bowl is difficult to turn, push the clip up while rotating.
- ASCO (off-white housings — FRP-019): Twist counterclockwise and pull down.
- Inspect bowls — a bowl full of water indicates a blocked auto-drain. Investigate before proceeding.
- Remove the filter element by unscrewing counterclockwise. Note its condition; if excessively contaminated before the scheduled interval, shorten the replacement frequency.
- Wash bowls in soapy water, rinse thoroughly, and dry with a clean cloth.
- Install new filter elements and replace O-rings as needed.
- Reinstall bowls in the correct housing in reverse order of removal, ensuring each bowl is fully seated.
- Reconnect condensate drain tubes.
- Slowly open the air inlet valve to repressurize. Inspect all connections for leaks.
- Reset the filter alarm via the touchscreen: navigate to Alarms → Filter Info and press the green button for each replaced filter element.
Contact South-Tek Systems
Phone: (910) 415-1880
Email / Ticket: support@southteksystems911.zendesk.com