Just thought I'd get my oar in on this one... I don't believe for one minute that our test proceedures are at fault when testing the flow delivery on the Colleague, I believe that they have a wear issue on the shuttle mech which leads to a more negative delivery, this wear happens over a relatively short space of time, the ones I've tested on our Avery system show this only after 2 years reasonable use.
Ask Baxter why they have recently revised the geometery of the Colleagues giving set!. (to give a more +ve flow)
I have been carrying out some tests on these pumps and have found that (so far) the delivery becomes increasingly worse under back pressure!, which is a little worrying as this is how you'd normally expect them to operate. Some of the pumps tested would pass the flow test with no back pressure (typically returning errors of -3%) but as soon as even a modest back pressure was applied (25mmhg) this was enough to push them over -5% and therefore fail...
I've got a lot more research to do but if you've experienced these problems let me know.
PS. You can also more than quadruple the occlusion level just by repeatedly running, unloading & reloading an occluded set. (The pressure gets trapped by the occluded end & the anti free-flow clip, on reload the pump zeros its pressure system on the line).
I can safely say I have no love of the Colleague!!!.
