How a De-gassing (self-venting) Head Works

A simple explanation and walkthrough by Andrew Hill (AKA .... Hilly)


How does de-gassing affect your prime?

When observing an EMEC VACO Pump you will notice a bottom and top valve, (see below picture).


These are the typical valves you would have on a normal/standard pump with the fluid flowing through bottom (suction) out the top (discharge/delivery). However, if for instance, you were to dose a chemical like sodium hypochlorite, which naturally gases off, while the pump sits dormant, gas builds up in the suction tube forming chlorine and air gas bubbles. When the pump is started the gas bubbles are drawn up into the pump head, causing it to lose prime in the suction line. The pump continues to stroke with no product being drawn up or discharged.

(Note, the EMEC VCO pump can run dry with no damage).


How do you stop this?

To alleviate this problem, you need a De-Gassing head, which allows the gas to escape back into the chemical drum. 

The EMEC VACO pump has three valves. The suction valve found at the bottom, 6 o'clock position, the discharge/delivery valve found at the the 10 o'clock position and the de-gassing (self-venting) valve found at the 12 o'clock position. (see picture below)

The de-gassing valves allows approximately 35% of the chemical along with the gas to pass back into the chemical drum avoiding any priming lose or chemical waste.


Degassing head diagram

What does this mean for pump efficiency?

While a standard pump have may have a delivery duty of 6 l/hr, as mentioned, the degassing head diverts approximately 35% of the chemical back into a drum allowing the gas to escape the head without causing loss of prime. Thus, the de-gassing head has a duty of only 4 l/hr.   All EMEC pumps with de-gassing heads are already de-rated to the stated dose rate when you purchase them, and are supplied with a full installation kit.

Please feel free to reach out directly using the form below for any questions about de-gassing heads.

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