I had a negative pressure failure also. Looked at my PDIA Hi=11.2. My deaer pressure was low, that's why it failed, but I don't think my PDIA Hi should ever be that high. Any thoughts?
Remove Air (0:10): Fill Program is performed even if no air is sensed to insure proper pressure reading during the test.
Get Negative TMP (0:30 - 0:45): TMP = VP – DP. After a positive pressure is achieved the UF pump is used to generate a TMP ≈ 270 then UF is turned off and a 30 second stabilization is allowed. (Watching: Ven.x-ducer & Dp #9 x-ducer)
• TMP must stabilize between (250 – 450)
• If the TMP does not stabilize in this range a message “Failed Stabilization” will be displayed
• If stabilization fails stop and troubleshoot to determine the cause
• Resume PHT after stabilization issue resolved
Negative Flow On (0:30 – 1:00): this is the first actual “pressure test” during the PHT. TMP must remain stable during this test and not change by more than +/- 20mmHg. This is a dynamic test for 30 seconds (hydraulics in motion). The TMP has been pumped up to a high pressure between 250 – 450 and must not fluctuate within those parameters.
(If TMP drops below ≈ 240 or the +/- 20mmHg tolerance, a “Remove Air” mode will start (0:10 - 0:15). Then go back into “Get Neg TMP”mode. This may add another 1:00 – 2:00 minutes to testing.)
Total Time ≈ 1:10 – 1:45min (3:00 – 3:15)
Positive Pressure Test:
Get Positive TMP (0:02 – 0:05): in this step the fresh valves are energized and loading pressure is used to push thru them to generate positive pressure at the Dp transducer. A pressure of at least +350 is achieved, then the pressure is reduced to +250. (Mainly watching “dead time” – a leak will cause no pressure to build and no dead time)
• After positive pressure is achieved a 20 second stabilization is allowed and TMP must remain within the range of (+180 to +350).
Positive Flow Off (1:00 – 1:30): Once a positive pressure has been achieved the flow is turned off and the TMP is monitored. (Flow off = flow pump, heater, & bal chamber valves all off; and the deaeration pump shortly after) The tolerance for positive flow off is +/- 30mmHg. The test is for 30 seconds.
• Only a hydraulic secondary leak will affect Dp reading during this test
• A leak in the primary or the balance chamber would not be felt at the Dp transducer unless two balance chamber valves were leaking on the same side of the balancing chamber
• If negative flow on failed and positive flow off passes – then the problem is located in the primary hydraulics or the balancing chamber itself.
Get Negative TMP (0:35 – 0:45): normal cycling is started and a TMP of > 0mmHg must be reached during this step. The UF pump may stroke during this step to achieve the proper pressure.
Testing (0:10 – 0:15): during this step the machine is monitoring the system to insure all is normal. (Waiting for TMP to stabilize >0 after UF pump strokes and stable, or it will Fail)
Total Time ≈ 1:55 – 2:00min
Possible Causes & tests to try
[Renal Web posts]
Condo & Temp alarm parameters correct
verify your condo and don't rule out a tiny leak on one of your concentrate uptake lines. I have many times seen the smallest of air bubbles seeping in on the bicarb line that raised havoc with alarms/pressure/tmp tests
Check ALL of your pressures (deair, loading and flow relief) are within spec
always put a gauge on the deaeration pump and see if your getting fluctuation if so the pump head is failing under pressure . Always best to run the tmp up manual to 400 to see worse case for the pump head. Also always good idea to do the same for the flow pump head
[pressure relief valve for the flow pump; deaer pump head]
Checked the incoming water pressure and it was high at around 24psi. I adjusted it down to 20 and the machine is now passing the test
Calibration of TMP – Pressure x-ducer #9 – or replace and recal
Check UF pump is working & fluid is being pumped
A good way to isolate is to open the Hansen door right when negative pressure test begins, causing bypass. That way, you can see if it is external leakage (blue Hansen to red Hansen) or internal (leakage in hydraulics).
If external: [Cracks in Hansen connectors; Hansen O-rings; Dialysate lines – connection to machine loose at back of machine; Flow indicator (bob) connections; dialyzer line filter, White shunt tubing on the shunt door worn out]
The positive and negative induced pressure tests described in the troubleshooting guide can be very helpful, as is following the procedure for flooding the hydro block by shorting the float switch position on the distribution board.
Induced positive pressure holding test then walk away for a half hour. If that doesn't produce a leak, then valve leak test.
Put the machine in dialysis mode, -then un-plug valve 43-clamp the output hose as well. Then simply disconnect of the air separator sensor leads. That will put it in a fill program and positive pressure will be applied. If you don't see a leak right away, - then do as was suggested and walk away for 15 - 30 minutes.
[Pre-UF filter (warped); UF output line (fluid sample); check valves; air separator hoses & screws (tighten); Diasafe filter]
Valve problem – 30,000+hrs
Do not believe the valve test on the debug screen, do a manual test it is faster and save you time.
[V-24 &25; BC valve test]
Check/calibrate level detector sensors – can cause multiple failures
Reseat the Power Control & actuator board
Actuator board
try piggy backing it to another machine, this will isolate whether it’s the hydraulics, or a board problem.
