Spent Hydrochloric Acid

Q. We make HCL drops out of our line and need to pump the spent acid to a holding tank. What is the best type of pump for this?  A.M.

A. While I do not know everything about your specific application, and assuming your spent hydrochloric acid is less than 20 percent, here are several thoughts:

• I prefer to use either an air-operated diaphragm pump (AODP) or magnetic drive pump in this application, since I do not like to use pumps with seals that eventually will leak.
• Wetted materials should be extremely resistant to the acid’s corrosivity. These materials include, but are not limited to: polytetrafluoroethylene (PTFE, Teflon), polyvinylidene difluoride (PVDF, Kynar), polypropylene, chlorinated polyvinyl chloride (CPVC) and Viton. Your pump supplier can provide you with its recommended materials and options for your specific application.
• Install true-union CPVC Schedule 80 valves with Viton or Teflon seals as close as possible to the pump’s inlet and outlet in order to isolate the pump and minimize the amount of acid that is released during pump change-out for service or replacement.
• If you decide to use an AODP, consider installing a short length of flexible tubing on both the inlet and outlet piping near the pump so that transmission of the AODP pump’s pulsations to the piping are minimized. This tubing is to be of the same or similar material as the pump and rated well above expected pressures. If you desire even more protection from tubing failure, you can purchase pre-fabricated tubing lengths that are reinforced with stainless steel braiding on the tubing’s exterior and are specifically designed for vibration/pulsation dampening.

Hope this is of some help.