Electronics 590-24 User Manual

Page 6

During operation the equalized air pressure from the pressure pot and the blast line input at
the mixing tee allows the MagnaValve to dispense shot into the mixing tee. It is necessary
to exhaust the pressure pot at the end of the blast cycle if mechanical valves are not pre-
sent. Failing to exhaust pressure pot air will force shot through the MagnaValve and down
into the mixing tee. It is not required to exhaust the pressure pot at the end of the cycle if
mechanical valves are used.

Although activating the mechanical valves (B) and (C) at the same time as enabling that
the MagnaValve (A) is possible, a sequenced starting procedure is preferable. Starting with
valve (C) will establish air pressure in the pressure pot. It takes about 1 second for the air
pressure to become established and stabilized in the blast hose all of the way to the blast
nozzle. Upon stabilizing the air pressure (about 1 second) open the second mechanical
valve (B). Then, about 1 second later, enable the MagnaValve (A).

Turn - On

Turn - Off

Step 1

(A) MagnaValve

Step 2

(B) pinch valve

Step 3

(A) MagnaValve

Failure to follow the above procedure will result in unstable and erratic operation that may
continue for up to 10 seconds. Dropping shot into the mixing tee while the air supply is sta-
bilizing contributes to a very unstable start up.

The turn off sequence should be done in reversed order. First turn off the MagnaValve (A).
This then purges shot from the mechanical valve (B), which means that, when it closes, it is
void of shot. This is an ideal condition for this valve, as closing with shot reduces its life ex-
pectancy. Next, about 1 second later, close valve (B) and then, about 1 second later, close
mechanical valve (C). If the blast hose is more than 3 meters long, delay the shut off of me-
chanical valve (C) longer to purge all of the shot left in the blast hose at the end of the
cycle.

Recommendations:

A. 1.

Use pipe unions to easily align or remove the MagnaValve. With the provid-

ed manual shut-off valve there is no need to drain the pressure pot of shot to clear
contaminants that have lodged in the MagnaValve.

B.
C. 2.

Allow about 6-inches (15 cm) between the MagnaValve bottom and the mix-

ing tee. If a mechanical valve (B) is not used substitute a 6” (15cm) pipe nipple to
provide the required spacing. This will isolate any air turbulence in the mixing tee
from the MagnaValve. Air turbulence causes abrasion in the bottom of the Magna-
Valve that decreases its life expectancy.