Pumping Problem

Any hydrogen will appear as bubbles in the stream, and at the levels introduced by an electrochlorination package there will be very little effect.

If there is a cavitation problem then it is unlikely that hydrogen bubbles are the primary cause; look elsewhere for it.

Yes ofcourse it will affect the vapour pressure and hence lead to cavitation in pump if suction head of the pump will not be sufficient to take care of this vapor pressure orthere is no provision to escape vapor.

Moto

"dissolved" hydrogen will do nothing in pumping. Think about pumping soda pop, no difference. The "dissolved" hydrogen will stay dissolved unless you (a) heat it up (b) lower the pressure or (c) allow another gas with a higher rate of solubility come in contact.

Thanks Vicini

There is a series of pipe diameter reductions between the tank exit and the pump impeller - my main point was if the hydrogen were to break out of solution is it feasible that the overall vapour pressure of the hypochlorite solution could be raised to such a high figure as 7 bar?

Matthew

If the pressure drop due to friction lwered the pressure lets say from 2atm to 1 atm, the hydrogen that comes out of solution would just flow backwards to where it came from.

Also, the hydrogen coming out of solution would cool the stream a little and some, say 10% would go back into solution.

Most pumps can handle a 5% free vapour phase of gases in a saturated solution and not cavitate. You pump manufacturer could speek to you about this.

I do not think the hydrogen will have much effect one way or the other. At 20C its solubility in water is .0016g/kg . It is true that if you are getting cavitation you can get very short lived "bubbles" with a very high pressure and temperature and this can erode the metal parts of the pump.