EBME Forums Forums Maintenance Technical Assistance Anti-Syphon & Anti-Reflux Valves

Has anyone come across any problems with areas using Anti-Syphon and/or Anti-Reflux valves in line sets used with syringe drivers?

I ask because I've recently been called to syringe drivers which are "Occluding", only to find that the occlusion levels are within manufacturers spec. I have tested one of these sets and the pressure built up between the syringe and the valve is about 180mmHg.

Any help or advice would be greatly appreciated.

Yes, we've had exactly the same problem on our using the Asena CC's and a/s valves; our results with the valve pressures were very similar although we did find the pressure dropped slightly once the valve had initally opened.

In the end we raised the default and max occlusion settings to compensate and stuck labels on the pumps to remind staff that a/s valves were to be used with evry infusion.

We have had quite a few problems with sets fitted with ant-syphon valves. to the point that we carried out our own servey. Although the manufactures of the sets supplied us with the specifications, we found that the cracking pressure varied quite significantly, some were well over the specifed limit. I think the answer is as Rob1234 said.UP the occlusion pressure to compensate and label the equipment accordingly. Obviously if the sets are reverted back to non syphon types at any time this would require a review.
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ROB1234,

If you are using Asena CC's, why didn't you put the pressure sensing disc in the CC set after the anti-syphon valve? Surely this would have eliminated the problem of requiring a higher occlusion limit as the sensing is done in-line?

I have had this problem with Asena GS's and Graseby 3300's.

One problem is that it seems to rear its head and then disappear for a while before resurfacing again!?

I agree with Paul that increasing the occlusion level is a solution, but if a line is used without an anti-syphon valve, the occlusion level will be too high.

This wouldn't be an issue with the old P3000's as the user could increase the occlusion alarm when required (although I have reservations as to whether the user being able to increase the occlusion alarm is a good thing!)

It appears that it is a case of the Devil or the Deep Blue Sea:
You can have an occlusion alarm to tell you when there is an interuption in delivery or you can have an anti-syphon valve to eliminate over-delivery, but using one negates the benefit of the other.



Thanks for your replies, though. At least I'm not alone in having this problem.

Has anyone tried comparing anti-syphon valves from different manufacturers?

I tried some from different manufacturers and found a large difference in the cracking pressure and the running back-pressures developed.

I was wondering if anyone else has come across this?