Solenoid Testing

Not sure what your solenoid looks like ..If it has a core which is pulled through a coil...then maybe it is trying to pull past the point of maximum thrunge (dunno the right word..but hopefully you know what I mean?)

e.g. You are trying to get it to pull the core through the coil and out the other side.

Hi Ashok,

you are correct in the fact that the force is greatest when the armature is at the stop. I am wondering if the force of the pump increases beyond the force of the solenoid when the armature is against it's stop. in most diaphram pumps the load in not linear but progressive as the volume increases. Also solenoids are not exact due to manufacturing and envrionmental reasons some will have slightly more or less force than others of the same type and size. measure the coil resistance to compare this will confirm manufacturing issues, higher tempratures will cause a solenoid to produce less force.

What are the pumps metering. If a meter flow is needed there may be an engineered reduction in force to keep a constant flow.

If I understand correctly the solenoid is used to press on the diaphragm to achieve the pumping action.

I would say they are made or wired that way to be as fast acting as possible. They must return fully to base before the next pulse arrives.

If you inspect the culprits you may find that the coil may be wired via one of the contacts set to disengage just before it reaches the end.

This slowing down should even out the flow. (remove the shocks)

For curiosity. What activate the solenoids?

I've got a funny feeling that you may be measuring force incorrectly. Either that, or you have described something oddly. When the solenoid is energized and has pulled against the stop, have you applied a force gauge (such as a spring scale) to the armature and tried to pull it apart?