the problem started with inter. high flow error,usually 20-30 minutes after mach passes test.then,occasionally an inter low flow error!!came to the conclusion after talking with a couple of techs that BC membranes probably shot.to make a long story short,put in a complete new BC assembly,zip strap all the hoses,and now TMP,neg stabilize and neg flow failures.now the laundry list of parts replaced:both pump heads and both pumps,diasafe fiter,all 6 hansen o rings,rebuilt u/f pump,pressure regular on hydro block,o rings on screw for hydro block,float switch,act bd and cable,test bd and cable,dialyzer in line filter,phoenix sample port in line.the 2 items i need to mention are:water from drain hose IS pulsing out every 3 seconds like normal but instead of "pushing" out the hose,it actually "burps" out with what seems like more pressure behind it.2nd point:when flow rate is 300,TMP displayed approx. 140,turn rate up to 800,TMP up to 300 to 320 range??? performed multiple pos press test-nothing.performed neg press test-nothing.performed tmp pump test,tmp held at 320 for 5 minutes.enough writing,anyone got a clue where to go next?thanks guys!!

Check the CFS to see if it's working correctly?

If it was flow errors only from the beginning I think its either pump heads, pumps motor brushes, or sticky valves,

new cfs and calibrated,complete new pumps and heads

When we were still running Hs we would go through cycles of this problem, alot of the times it was BC valves V31,33,35,37 mostly but sometimes V32,34,36,38. Most of the time it would be one off the first bunch I listed.

but as i said,replaced complete BC ASSY(includes valves)

It's got to be a valve that's sticking somnewhere. Since you have put in a new BC with new valves, you can eliminate that. 41/29 or 24/26 valve combo's? It can be very frustrating because a valve may be rusty and sticking just a little without a valve error showing up. Let us know what happened.

Sorry, should have read your first entry a little closer.V25 could be the culprit even.Double check the wires to you bc valves.My buddy is saying there is a small chance on the sensor bd since it senses bc switching. good luck

Whats your loading pressure? also might wanna check v43.

Try Valve # 30

replaced V41 & v29.loading pressure=24

If you suspected a BC problem did you do a BC volume test? Based on what you indicated a high flow error, one could blame the switching transducer. Then you had a low flow error which can be caused by not enough water(float switch).
Failing the Neg. stabilize, Neg. flow on indicates an air leak somewhere. Are the wires from the BC vales all in the right place on the distribution brd.? The unusual flow at the drain (burping) could be caused by a valve that is not working properly. Don't assume that all the valves on the new BC assembly are ok. What is your cond. when the machine is running at different dialysate flow rates?

Just another thought try the actuator board, valve female connector if you did replace the wires also, at one time while I was replacing a valve and ended up using the wire that was for another valve, eg. one valve uses pin 1 & 3 the other uses 1 & 5 for control signals from the actuator drivers, last thing is to reconfirm all your pressures so you can eliminate your pumps and the hydroblock.

mjpc,
Make sure the BC valves are connected to the right plugs. Also, in addition check the "O" ring in the dearation orifice

pato

just to give everyone whos been helpin an update on this problem,BC membranes were fine in old assy,V29 & 41 replaced,all harness's hooked up properly.when turning machine on,go into dialysis mode,3 sec after,flow error and now blowing clear lines off ck valves 63,64.wiced back pressure throughout system.will keep you guys posted!thanks for your continuing help!