Differential Pressure Hand Pumps

Have you considered a syphgmomanometer (blood pressure tester) squeeze bulb?

You'd still have to go easy because even those can generate close to 80" w.c. of pressure (the one attached to this DP does, anyhow).

The cal lab for a place I worked years ago had a pneumatic dead weight tester and I seem to recall that they had a custom weight or two cut for it for the low pressure cal points for low pressure. I don't know if the manufacturers even cut custom weight plates anymore.

If memory is right the lowest pressure for that one was about 4" or 5" w.c.

I'm not sure if the regulators in a Wally box handled those low pressures or not.

GA to Eltech for such an obvious solution!

Use a vertical "U" tube, long enougth each branch 60" , fill with water , up to 30 " free both end , conect one end to the sensor , add water at the open side , to fill just 1" , step by step .

You will have a pressure generator the most perfect you can get , no conversion, just use a rule to measure the difference between each branch

You do not need to wreck anything. Silicon pressure gage modules do come in all different strenght. For higher precision some are selfcalibrating too. Normal electronic catalogues list most of them. As with any equipment the high end value and resolution are mutual tradeoffs.You have to know, what you need.

When you buy factory calibrated, or selfcalibrating modules, your question is moot. And I do doubt very much, that you can do a better iob, laser trim the chip, or store the correction values in an on-chip prom. Not for the price differential.

Pop down to the Chemist. For $18 you can buy an enema. Ideal for low pressures, and available everywhere.

With a nod to the instruments for blood pressure and constipation, allow me to introduce to you, the 'Hand Aspirator'.

Commonly available. Just a Google away...

Iris hit it on the head, use a blood pressure monitoring hand pump, and use it gently.