Self-injection via peristaltic pump of sulphuric acid due to negative pressure. Help needed.

[Reinou]

At my swimming pool I keep having problems with the (Sugar Valley) peristaltic pump for the PH-min (sulphuric acid solution). Because the pool is located lower than the technical room, the pipes empty when the filter pump is off. With the negative pressure that is created, the sulfuric acid is sucked in when the peristaltic pump is stopped in certain positions. Replacing the rotor and peristaltic tube had no effect.

Has anyone maybe dealt with this problem and knows a solution? Or could a magnetic pump be the solution (do they completely close, even at negative pressure)?

Thanks for the help!

 

[Bama Rambler]

Welcome to TFP.
Can you give us the make and model of the injection pump? A picture of the head end may help too.

Most small peristaltic pumps have three rollers in the head so no matter which position it stops at least one the rollers are occluding the tubing preventing a gravity or suction flow situation.

 

[Reinou]

Hi Dave,
Thanks for your reply. Meanwhile I have been in contact with a company that sells professional pumps, amongst others magnetic pumps.
They told me even a magnetic pump occasionally can has this problem with negative pressure in the system. For this they advised me a Multifunction valve, which has an Anti-syphon valve mode.
I ordered this valve and put it into place. I'll post my experiences with it after some time, to help others.