How the screw press works
This is a two-shaft multi-disc screw press, custom-built for us in China to process restaurant fats, oils and grease (F.O.G.). Polymer makes wet F.O.G. sludge clump, a slow screw drags those clumps uphill through a stack of steel rings, and the water squeezes out between the rings. What comes out the top is a damp cake.
The path through the machine
Seven things happen in order. Tap each one to isolate it. The yellow tags are the same device names printed on the wiring drawings and stuck on the parts in the cabinet.
What the water balance looks like
Worked example using general figures, not a test of this unit. Published ranges for comparable presses are 10,000–50,000 mg/L feed (1–5% solids) and cake below 80% moisture. The manual doesn't give feed or cake targets for this model. Our polymer, sludge type and speed settings decide the real numbers.
Rings and the back pressure plate
A belt press or filter uses cloth, and cloth blinds. This machine has no cloth. The filter is a stack of thin steel rings with hairline gaps between them, threaded onto the screw.
Fixed rings are locked in place. Moving rings sit between them and ride on the screw, so the turning thread keeps nudging them. That constant small rubbing wipes the gaps clear, which is why the screw can run for hours on sludge without a heavy backwash.
Pressure comes from two places. The thread pitch tightens and the ring gaps narrow toward the discharge end, so the material gets less and less room. Then the back pressure plate at the end restricts the exit. Its gap is the one mechanical adjustment the operator sets by hand.
Keep that gap at 4 mm or more. The manual says a smaller gap overloads the screw body and shortens the life of the moving rings and screw shaft. At 0 mm no cake can come out. After any adjustment, tighten the plate's fixing bolts.
The drawing shows the general design of this machine type and is not to scale.
Finding it on our machine
Tap a number on a photo to see what it is.
Feed end
Discharge end
Inside the press tanks
Run the panel
This door is a sim of ours, using the same press logic. It opens in Auto and running. Press Auto stop and watch the feed quit while the screws keep turning. Then trip a fault, follow its card and reset it. You can also tap a fault lamp on the door to read its card. If you press something out of order, a popup explains the problem and the safe way to restart. The clock runs 60 times faster than real life.
Solid outline: contact closed. Dashed red: contact open, and this is what is stopping that device.
Inside the cabinet
The three timers
The close-up shows the labels and dials, so these are now confirmed against the drawings. Dial settings can be changed, so check them on site.
| Dial reads | Timer | Job on the drawing |
|---|---|---|
| 30 S / 10 M | KT1 | Pulses wash valve Y1 while either screw runs: about 30 seconds of spray every 10 minutes. The manual's factory setting is 25 seconds every 15 minutes, with a 20-second minimum. |
| 30 M / 00 | KT2 | Run-on after Auto stop. The dial looks like 30 minutes, but the manual's factory setting is about 5 minutes, so confirm this one. |
| 60 M / 02 S | KT3 | Pulses vibrator contactor KM7 on the separator side, about 2 seconds each hour. |
Where the power goes
Sheets 1 and 2 show how the supply splits. The overload figures are adjustment ranges in amps from the drawings. Each dial still has to be set for the motor actually connected, so check those settings against our pump and motor nameplates.
| Sticker in cabinet | Name on drawing | Rating | Feeds | Overload range |
|---|---|---|---|---|
| QF1 | QF1 | C 63 A, 3-pole | Main supply. Also runs the cabinet fan and Power lamp directly. | None shown |
| QF2 | QF3 | C 63 A, 3-pole | Drives U1, U2 and the screw motors | In the drive |
| Screw motor fans through KM11, KM12 | None shown | |||
| Mixer, KM2 | FR2 2.5–4 A | |||
| Sludge pump, KM3 | FR3 12–18 A | |||
| Dosing pump, KM4 | FR4 4–6 A | |||
| QF3 | QF4 | C 32 A, 3-pole | Separator main motor, KM5 | FR5 12–18 A |
| Submersible sewage pump, KM6 | FR6 5.5–8 A | |||
| Vibrator, KM7 | None shown | |||
| QF4 | QF2 | C 6 A, 1-pole | Control circuit, through the E-stop | None shown |
Breaker labels are shifted from the drawing
The wire tags under each breaker show what it really feeds. Cabinet QF2 carries X1/Y1/Z1, which the drawing calls QF3. Cabinet QF3 carries X2/Y2/Z2, drawn as QF4. Cabinet QF4 carries control wire 1, drawn as QF2. Use the table above, and have Blake correct the stickers or drawing. These ratings were read from a photo, so confirm them on the breakers.
2.05 kW is not our supply size
That figure is the press alone: 0.75 kW for each screw, and the remaining 0.55 kW is probably the mixer. The separator motor alone is 4 kW. Its 13.82 A rating sits inside the 12–18 A overload range, and the sludge pump uses that same range, so expect a similar size pump. Size the supply from everything connected.
Motors and gearboxes
| Part | Rating plate says | What it means |
|---|---|---|
| Press motors (2) | XL-Motor YVF2-80M2-4-W, 0.75 kW, 230 V, 60 Hz, 3.44 A, Y, IP55. Constant torque 5–60 Hz, constant power 60–100 Hz | Built for variable speed. The manual's general 20–120 Hz drive range goes past this plate, so stay within the plate. Check the drive's motor settings against it too. |
| Press gearboxes (2) | Zongli ZKLAF77R37-YVP0.75-4P-291, 0.75 kW, 1400 in, 4.8 r/min out, built 2026.2 | At that rating the screw takes about 12.5 seconds for one turn. The speed dials change this. YVP marks it as made for variable-speed use. |
| Press motor fans (2) | G80A, 25 W, 0.12 A, 230 V, 2700 r/min | The fan cools the motor even at low speed, so it runs from KM11 or KM12 instead of the drive. Check its rotation arrow after any wiring work. |
| Press drives (2) | ATV320U07M2C, 0.75 kW, 1 HP, 200–240 V | Single-phase input, which matches L1 and L2 only on sheet 1. Three-phase output to the motor. |
| Separator motor | 112M-4, 4 kW, 230 V, 60 Hz, 13.82 A, 1728 r/min, delta, power factor 0.82, efficiency about 88.6%, IP55, class F, 36 kg, duty S3-75% | Starts directly through KM5. Have Blake confirm the FR5 dial suits 13.82 A. S3-75% is an intermittent duty rating, so ask the maker whether this motor may run continuously. |
| Separator gearbox | Shanghai Zongli, input 1400 r/min, output appears to read 98 r/min, built 2026.2. Type is blurred. | From those figures, a 1728 r/min motor would turn the screw at very roughly 120 r/min. The red sticker says it has been filled with lubricant. Check the sight glass before starting, and ask the maker for the lubricant type and whether the cap on top needs opening. |
Gearbox breather and oil
Remove the rubber ring on each breather before running. The English tag on the valve says to unplug it completely when in use, and the ring still looks fitted in our photos. The yellow sticker appears to say the box is already filled. An informal translation also says to check oil every 3,000 running hours or 6 months, using VG220 or VG320 gear oil, so have the maker confirm that part.
Ignore the manual's 380 V drive setting
Manual page 15 lists a typical motor voltage of 380 V and a 360–460 V range, and the manual's site requirements list a 380 V 50 Hz supply. Those are general figures. Our nameplate, motors and ATV320U07M2C drives are all around 230 V, and the drive's guide lists this model as 200–240 V single-phase. Have an electrician confirm the drive holds our motor plate values: 230 V, 60 Hz, 3.44 A. Never set 380 V here.
The motor wiring sticker
A yellow sticker gives general motor rules. Standard motors shouldn't run on a drive, and motors with a separate fan need the fan wired separately at the voltage on its plate. It says that is usually 380 V, but our plates say 230 V, so follow the plates. A 4 kW motor is delta only, matching the separator plate.
What the drawings reveal
Empty polymer does not stop the feed
The dissolving-tank float (terminals 36/37) sits only in the dosing pump rung, and a dosing trip FR4 drops only KM4. The sludge pump keeps running, so raw undosed sludge can go into the press with only the fault lamp to warn the operator. Watch the polymer tank, or have a PLC act on the fault signal. A float going low gives no lamp or signal at all on these drawings.
Drive switches still matter in Auto
SA4 SA5 SA6 only work in Manual. SA11 and SA12 sit after the point where the Manual and Auto paths join, so a drive switched off stays off in Auto too. The manual says Auto makes these switches invalid, but our drawing shows otherwise. If a screw won't start, look there first.
Auto stop is not an instant stop
Auto stop drops KA5. Feed, polymer and mixer stop at once. The screws stay latched through their own contacts until KT2 times out. Turning SA2 out of Auto appears to skip that and stop the screws at once, which leaves sludge in the barrel. The manual warns that Stop may not stop the machine right away because of this timer, so always use the E-stop in an emergency.
Float terminals look jumpered
Yellow jumper wires sit at the end of the terminal strip, right after the P terminals, where sheet 6 places 31/32 and 36/37. If those are the jumpers, the pumps will start with no floats, but nothing protects them from running dry. Confirm this, then replace each jumper with its float before service. The demo's low-tank buttons show how the circuit acts once floats are wired.
Manual feed has no high-level cutoff
LVS1 sits only on the Auto branch, so the electrode rods can't stop KM3 in Manual. Someone has to watch the level. In Auto, sludge buildup on the rods can cause a false full reading, which the manual lists as a cause of a stopped pump.
A drive fault only stops that drive
KA20 blocks KM11 and KA21 blocks KM12. The other shaft, the feed and the polymer carry on. Those fault relays also close a shared signal to terminal P4, labelled "Mouse Fault" on the drawing, which looks like a translation slip for a general fault. The drive wiring uses its R1B and R1C terminals, normally the contact that closes on a fault or loss of drive power, so both drive fault lamps may also light whenever the press breaker is off.
The other machine: the separator
The second machine looks like the separator on this panel. Sheet 5 labels its level rods "Solid-Liquid Separator", and the door calls it "Solid liquid equilibrium". It's a different kind of machine. The press uses polymer and squeezes water out of sludge. This one strains raw liquid through a steel screen, with no polymer, and then a screw carries the caught solids away. Its port labels show in the photos, but no manual or nameplate for it has been reviewed, so this description of how it works is a best reading.
How it runs
The submersible sewage pump KM6 sends liquid to the water inlet at the top rear. It enters an open trough behind the screen under a welded box, which likely calms the flow. It then spills over the lip and runs down the tilted wedge-wire screen. Liquid drops through the fine slots into the chamber behind and leaves by the filtrate port. Solids stay on the face of the screen and slide down to the screw trough, whose perforated lining lets more liquid drain out.
The main motor KM5 turns a screw along the trough, carrying solids into a perforated cylinder at the end of the machine, where more liquid can drain before the solids leave. The vibrator KM7 pulses on timer KT3 to help shake solids free.
In Auto, the pump only runs while the main motor runs and level relay LVS2 allows it. That means the screw is moving before any liquid arrives. Sheet 5 shows rods E4 to E6 for that level relay, but they aren't visible in the photos, so confirm which tank they belong in. The main motor has no drive or speed dial on the drawings, so it runs at one fixed speed.
Front
Rear
Drive end
The separator paperwork doesn't match this panel
The panel diagram and two wiring pages look like the separator's own standard set. They show a 500 × 750 mm panel, a 2.2 kW "extruder", a submersible pump listed at both 2.2 and 1.5 kW, a 550 W water pump, a 25 W "flushing gearbox" and a 415 V to 220 V transformer. Our machine has a 4 kW motor, a vibrator and this shared 230 V cabinet, and none of those flushing parts appear on our terminal list. Don't wire from those pages.
What those pages do tell us
"Extruder" suggests that the main motor drives a screw that pushes solids out. The flushing parts raise a question about the small steel tube, which has no valve or pump on our drawings. Ask the maker whether our unit needs a flush supply and how it should be run.
Which instructions carry over
The press manual doesn't mention a screen or vibrator, so treat anything marked "Maybe" as good practice until the separator's own manual is available.
| Instruction | Separator? | Why |
|---|---|---|
| Lockout, E-stop and cabinet warnings | Yes | Same cabinet. Sheet 2 shows it fed through its own breaker from the same main. |
| Overload reset steps | Yes, with a change | Same type of device, with FR5 and FR6. Set SA8 to Stop instead of SA2. |
| Motor, wiring, bolt and pipe checks | Yes | These apply to any motor, pump and pipework. |
| Wrong rotation warning | Yes | A reversed screw won't discharge. Match the arrow by the gearmotor after any wiring work. |
| Don't let solids dry inside during idle time | Maybe | The reason carries over, but the 1-week and 2–3 day limits were written for the press. |
| Indoor storage and don't store water in it | Maybe | Sensible, but the warranty terms cover only the machine named on that warranty. |
| Polymer, floc and mixing tank steps | No | No polymer or mixing circuit appears on its side of the drawings. |
| Moving rings, back pressure plate, 4 mm gap, wear hours | No | Those parts and figures belong to the press. Don't apply the 4 mm rule to the end housing. |
| Drive error reset, speed adjustment | No | The separator has no ATV320 drive on the drawings. |
| Spray timer and solenoid steps | No | Y1 and KT1 are press circuits. The separator's tube has no valve on the drawings. |
Before running it
The trough has a hinged panel that looks like a cover, but the drawings show no interlock on it, so opening it won't stop the screw. Confirm the guarding with the maker, and lock out power before opening it. In Auto, the vibrator can pulse on its timer and the pump can restart on its own. Keep hands away from the roller arm and lever at the discharge end. The motor cable is unconnected in the photos, so have Blake check rotation after connecting it.
Cleaning the screen
Clean the screen with a pressure washer. Lock out the power first, and keep water away from the cabinet, motor and vibrator box. Keep the nozzle far enough back to avoid bending the wires, because damaged wires can ruin the screen. The maker still needs to confirm its slot size and flow rate.
Field connections from sheet 6
The manual rates the panel's output contacts at AC 220 V or DC 24 V, 2 A. They are dry contacts, so our PLC supplies its own signal voltage.
| Terminals | Direction | Meaning | Closed by |
|---|---|---|---|
| 18 / 41 | In | Press remote start from a plant PLC | PLC contact, with SA1 on Remote |
| 55 / 56 | In | Separator remote start | PLC1 contact |
| 31 / 32 | In | Sludge tank low level | Float, in series with sludge pump |
| 36 / 37 | In | Dissolving tank low level | Float, in series with dosing pump |
| P1–P2 | Out | Press remote enabled | KA3 |
| P1–P3 | Out | Press running | KM11 KM12 KM2 KM3 KM4 |
| P1–P4 | Out | Press fault | KA20–KA24 |
| P1–P5 | Out | Separator remote enabled | KA13 |
| P1–P6 | Out | Separator running | KM5 KM6 |
| P1–P7 | Out | Separator fault | KA25 KA26 |
Starting it up
This condenses the manual's start-up pages and adapts them to our panel. The press manual covers the whole PJDL series and doesn't address F.O.G., so use it for general operation. The wiring drawings are the reference for this panel. Have an electrician do the supply wiring and phase check. Settle the jumpers and missing relays on the notes page before putting it in service.
First-time setup (once)
- Check the machine sits level on its specified bolts, with service room around it. If it ever has to be lifted, use rated nylon slings, not a forklift, and never lift by the screw body or let slings touch the spray pipe, piping, wiring or panel.
- Check that bolts are tight, and keep the T-shaped hex wrench with the machine.
- Protect the tanks and pipes from freezing.
- Connect water at 0.2–0.3 MPa (about 29–44 psi), and check for leaks.
- Remove the gearbox breather rings.
- Have Blake tighten the cabinet terminals and measure the supply voltage at them.
- Check rotation: follow steps 3 and 4 of Every power-up, then set the Manual/Stop/Auto switch to Manual, then run each motor briefly. Screws should turn counterclockwise viewed from the front of the discharge. The mixer should turn clockwise viewed from above.
- If a pump or mixer runs backward, cut the main power and have Blake swap two phases. The manual says R and T at the cabinet, but our screws run from drives on a shared supply, so have Blake decide where to correct each motor. Repeat this check after any wiring work.
- Check each pump, and never run it dry. Return all switches to off.
Every power-up
- Check that the Vent Port valve and the maintenance valve are closed, and the water supply is on.
- Check the polymer and sludge tank levels by eye.
- Set the Manual/Stop/Auto switch to Stop and turn every OFF/ON switch off.
- Turn on the main breaker and check the Power lamp, then turn on the branch and control breakers.
- Set the Manual/Stop/Auto switch to Auto and press the green Auto start button.
First sludge (once)
- Work out the feed and polymer flow with the calculator below.
- Power up as above, with the feed and polymer settings ready.
- Set the feed with the level adjustment pipe, inside the V-shaped weir range. Turning it left raises the pipe and increases feed. Turning it right lowers it and reduces feed. The weir ruler shows roughly how much is going through.
- Adjust the dosing pump dial while it runs.
- Check for flocs about 5–10 mm across in the mixing tank.
- Be patient. Pressure builds slowly, and the manual says a formed cake takes about 60 minutes.
What differs on our panel
The manual covers a whole series, so it describes parts our machine doesn't have:
- 24-hour timer (TS-1): not on our drawings, so Auto doesn't run to a daily schedule.
- Mixer drive (INV-2): not fitted. Our mixer runs at one speed through KM2, so the manual's mixer speed adjustment doesn't apply.
- Starting Auto: the manual says switching to Auto starts it. Ours also needs Auto start pressed.
- Main breaker (ELCB-1): the manual shows an earth-leakage type, and its test sheet lists leakage protection. Our drawing shows a plain breaker, so ask our electrician what ground-fault protection we need.
- Spray and fan switches: the manual shows separate switches inside the cabinet. Ours use SB2 and KT1, and the fan runs with main power.
Feed and polymer calculator
Uses the formulas on manual pages 21–22. Its example of 12 kg-DS/h at 10,000 mg/L gives 20 L/min (5.3 gal/min) of sludge, and 18 kg-DS/h at 0.6% diluted 1,000 times gives 1.8 L/min (0.48 gal/min) of polymer. The starting values below are examples, not recommendations, and aren't F.O.G. figures. Use the maker's numbers once we have them. Our polymer supplier or a jar test sets the real dose.
Our nameplate rates the press at 70–140 kg-DS/h (154–309 lb/h). Gallons are US gallons. Compare the polymer figure with our dosing pump's performance curve.
Mixing polymer for a jar test
This follows Hubbard-Hall's general jar-test method. It doesn't give a F.O.G. dose, so get the polymer and starting range from the maker or supplier. Follow the supplier's instructions and SDS for the product in use.
Liquid polymer, 0.1% stock
- Shake the polymer bottle.
- Mix 250 ml of water fast enough to form a vortex.
- Inject 0.25 ml of polymer into the vortex and mix for 1 minute.
- Stop mixing and let it age for 30 minutes.
Powder polymer, 0.1% stock
- Weigh 0.25 g of powder.
- Mix 250 ml of warm water fast enough to form a vortex.
- Sprinkle the powder in grain by grain, so it doesn't clump.
- Mix until fully dissolved, about 30 minutes. Cold water may take longer.
- Let it sit for 30 minutes without mixing.
Dosing the jar
In a 1 liter jar, 1 ml of 0.1% stock equals 1 ppm. Add only diluted polymer, never concentrated polymer.
Hubbard-Hall says 5–10 ml often flocculates general wastewater. The press manual's 0.6% example at 10,000 mg/L works out to about 60 ml per liter. Neither figure is a F.O.G. dose.
Handling
- Label each bottle with the product, strength and date. Hubbard-Hall says cationic solutions last only a few days and anionic solutions several weeks.
- Don't use a blender, which shears the polymer and makes it ineffective.
- Don't use samples that have frozen.
- Wipe up spilled powder dry, because wet powder makes the floor slippery.
Tuning it
After commissioning, the manual says routine running should need nothing beyond replenishing polymer. It does say to check the sludge regularly, and if the concentration swings by about 10% or more, the cake and throughput will change enough to need adjustment.
| To do this | Do this | Watch for |
|---|---|---|
| Raise throughput | Speed up the screws and feed more through the level adjustment pipe | With the plate gap unchanged, sludge can build up, overload the motor and wear the rings and shaft faster |
| Lower throughput | Slow the screws and reduce the feed through the level pipe | Too much water in the barrel if the screws are too slow for the feed |
| Recover from wetter cake when sludge thins | Feed more sludge to restore the solids load and barrel pressure | Keep the level at or below the high mark, H position, and keep the sludge flow continuous |
| Make cake drier | Lower the screw frequency, or reduce the back pressure plate gap | Less throughput at lower speed. A smaller gap means more wear. Never below 4 mm |
| Make cake wetter, or raise capacity | Raise the frequency, or open the plate gap | Stay inside the motor plate range. After a speed change, recheck feed and polymer |
| Set the back pressure plate | With SA2 at Stop and the screw stopped, open the discharge cover. Jog the screw in Manual until the bolt is on top, then stop. With the power locked out, loosen it with the T-wrench, set the gap, and tighten | Don't over-tighten. Don't change it if daily checks show no problem |
Use the door dials R1 and R2 for speed. The manual warns against adjusting the drive inside a powered cabinet, against operating the panel with wet hands, and says to wear insulating shoes.
Don't let the feed sit so high that the level keeps hitting the top rod. The manual warns that frequent stop-start operation shortens pump life and makes cake moisture and throughput unstable.
Troubleshooting
This summarizes the maker's manual, which uses awkward translations. "Alum flower" means floc, and "liquid medicine" or "polymer drugs" means polymer solution.
| Problem | Check, in order |
|---|---|
| Won't run in Auto | Mode switch, E-stop, tripped overloads, drive errors, and any abnormal state at the polymer system or sludge tank. Also check the sludge tank level. |
| No sludge reaching the mixing tank | Pump failure, air in the pump, blocked or worn impeller, tank already overfull, buildup on the electrode rods, closed valve or blocked line. |
| No cake coming out | Sludge getting into the barrel, blocked pipe to the barrel, floc size, and a back pressure gap that is too tight. Solids can also leak out through the rings when floc is poor. |
| Wet cake, small flocs | Sludge too thick (reduce feed), wrong pH for our polymer, changed polymer concentration, weak or blocked dosing, debris around the weir or level pipe. |
| Wet cake, large flocs | Sludge too thin (raise feed), changed polymer concentration, debris in the metering tank. Then check for overdosing. |
| Signs of too much polymer | Thick sludge around the feed pipe or stuck in ring gaps, poor filtering, viscous filtrate, or drier cake with rising motor current. |
| High solids in the filtrate | Too much feed, or screws too slow. |
| Leaking from a seam | Too much feed, screws too slow, or poor floc. |
| Moving rings not moving | Worn rings. Contact the maker or agent. |
| No spray | Closed water valves, clogged sprinkler head, timer on-time at 0 (set above 20 seconds), failed solenoid valve, spray switch or supply. |
| Sludge won't discharge after motor work | Motor running backward. Cut the power and have the wiring checked. The manual warns that reverse running can damage the machine. |
Resetting a tripped overload
The operator does this reset. Set the mode switch to Stop first, because the machine could start and injure someone when the relay resets. Turn off main power, fix the cause, press the blue RESET button on the overload (the manual says white, but ours are blue, with a red STOP), then return to the operating mode. A very hot relay may need to cool first. If it keeps tripping, stop and contact the maker or agent.
Recovering from an E-stop
Set the Manual/Stop/Auto switch (fourth row, fourth from left) to Stop first, because the machine could start and injure someone when the button releases. Twist the button to the right to release it, deal with the fault, then choose the operating mode and restart.
Clearing a drive error
Set the mode switch to Stop, fix the cause, reset the drive as its own manual directs, then return to the operating mode. The press manual mentions a program or reset key, but our ATV320 has an ESC key and a green dial that also works as ENT. Menus are REF for speed, MON for monitoring and COnF for setup. The drive code lookup below explains each error code.
Drive code lookup
When a drive fault lamp comes on, type the code from that drive's display. Who handles each code is a suggested default for this machine, so review it against our procedures. The list comes from the fault chapter of Schneider's ATV320 programming manual, NVE41295, in its 04/2018 edition. Newer drive firmware can differ.
Fault by fault
Fault lamps and low tanks don't need a dial turned. Fix the cause, then reset. Every overload stays at its set value.
Causes and reset order come from the maker's manual and our drawings. Which machines keep running comes from the drawings. These steps are general for each pump until the pump manuals are added.
Manual names on our panel: COS-1 is SA2, EMS is SB1, CSL is each OFF/ON switch, OL-0 is the fault lamps, INV-1 is U1 and U2, WL-1 is H1, TLR-2 is KT2 and TLR-3 is KT1.
Care and warranty
Daily checks
Polymer and sludge tank levels, by eye, before starting and during each run, because the panel has no low-tank alarm. Motor running normally, with no strange noise or vibration. Plate gap suitable, and cake moisture steady. Normal filtrate solids. No buildup around the metering tank weir, the horizontal tube or electrodes. Good floc forming.
Periodic checks
Cabinet lamps, motor heat and current, timers and drives running to their settings, drive display, moving rings moving, filtrate leaks, solenoid valve operation and leaks, metering tank feed amount, and loose bolts, pipes and valves.
Idle more than a week
Use 2 to 3 days if our sludge dries easily, because dried sludge can damage the machine on restart. Drain and wash the mixing tank, running the mixer as it drains. Open the back pressure plate fully and run the screws in Manual for 1 hour. Wash the barrel, then turn off the main power.
Idle more than 3 months
Do all of the above. Keep the cabinet door closed and the room air moving to prevent rust. Run the machine in Manual every 3 months to keep the cabinet relays from rusting.
Wear parts
The manual's 300 model, which should cover our PJDL-302, lists about 20,000 running hours for dewatering-section moving rings and 50,000 for the screw shaft. These are approximate and are not warranty periods. Keep a log of running hours.
Warranty
12 months from the shipment date, so check our shipping papers. The nameplate says 2026.03, so it may run out around March 2027. Consumables are excluded: moving rings, screw shaft and nut, bearings, solenoid valve, baffles, stickers, panel lamps and fuses. So are unauthorized disassembly or modification, running beyond spec and repairs at other shops.
Before first use, the warranty terms require indoor storage out of rain and leaks, at −10 to 40 °C and below 85% humidity with no condensation. Keep it away from corrosive gas and salt, protect it from nearby construction, and don't connect power or store water or sludge in it.
Before anyone works on it
No alarm for low tanks
No lamp or signal warns when the polymer or sludge tank runs low. Once floats are wired in, a low tank only stops that pump, and its blue switch light goes out. If the polymer tank runs out, the sludge pump keeps feeding untreated sludge into the press. While the float terminals are jumpered, nothing stops either pump from running dry. Check both tanks by eye before starting and during each run. If polymer is low, press Auto stop and refill it before restarting.
The E-stop is not isolation
On the drawings it only breaks the control circuit. The drives, cabinet fan and Power lamp all stay powered, and the Power lamp staying lit is expected. Lock out the supply before opening covers or reaching into the cabinet.
Green is a live wire here
The cabinet label marks phases A yellow, B green and C red, with PE on a yellow label and yellow-green terminals. The supply leads match, and so do the screw motor fan cables, which use yellow, green and red conductors. In US wiring, green usually means ground, so a US electrician could easily make a dangerous mistake. The motor cables use black, blue and brown, with yellow-green for ground. Point this out to anyone working in the cabinet, and consider relabeling.
The drives hold a charge
The label on each Altivar drive says to remove all power and wait 15 minutes before servicing. Follow that even with the breakers open.
Moving parts under the covers
The machine carries a pinch warning at the drive end and a goggles warning on the tank. The manual says to turn off the power before cleaning the screw body. In Auto, the level rods can restart the pumps with no one at the panel, and in Remote a PLC can start the press.
Hands out while it can run
The manual says not to run with the side cover open, and not to put hands or objects into the cake outlet or the mixing tank while running. Don't touch moving parts in Auto even when the machine looks idle, because it can restart by itself.
Polymer and sludge
Polymer spills turn floors extremely slick, and sludge carries its own exposure risks depending on its source. Get the SDS for our polymer and treat the source of the sludge as part of the hazard review.