Operating instructions

5.2 Liquid end

The diaphragm (2) hermetically shuts off the pump volume of the dosing

head (4) towards the outside. The suction valve (1) closes as soon as the

diaphragm (2) is moved in to the dosing head (4) and the feed chemical

flows through the discharge valve (3) out of the dosing head. The dis‐

charge valve (3) closes as soon as the diaphragm (2) is moved in the

opposite direction due to the vacuum pressure in the dosing head and

fresh feed chemical flows through the suction valve (1) into the dosing

head. One cycle is thus completed.

Fig. 7: Cross-section through the liquid end

1 Suction valve

2 Diaphragm

3 Discharge valve

4 Dosing head

5 Backplate

13 Safety diaphragm

5.3 Integral relief valve

The integral relief valve normally operates as a simple, directly controlled

bleeder valve. As soon as the pressure exceeds the pressure value, which

is set using the large spring (1), it lifts the ball (2). The feed chemical then

flows out through the hose connection (5), e.g. into a storage tank.

The integral relief valve can only protect the motor and the gear, and then

only against impermissible positive pressure that is caused by the

metering pump itself. It cannot protect the system against positive pres‐

sure.

The integral relief valve works as a bleed valve if the rotary dial (3) is

turned clockwise up to the "open" stop: This relieves the high force caused

by the large spring (1) which was acting on the ball (2) - the ball is now

controlled by the low force of the small spring (4). The integral relief valve

is, when used in this way, a priming aid for starting up the pump against

pressure.

Functional description