Novag novaG-2K, Руководство по обслуживанию, Страница: 16 / 23

novaG
– 2K
Service Manual
16/23 Issue 1.6 Ref. NR-00026-ENG
http://www.novag.eu/
Proportioning Pumps
WARNING!
Before resolving any kind of defect, make sure all of the pushbuttons are
off, that the general switch is in shutdown position and that the unit is disconnected from
the pneumatic supply source.
PROBLEMS SOLUTIONS
The pumps fail to maintain the pressure when the unit is shut down. 1
There are pressure differences between the proportioning pumps. 1-2-3
There is cavitation in the proportioning pump. 1-2-3
The proportioning pumps do not change direction. 4
The proportioning pumps fail to move and the direction indicator lights are
out. 4
The movement of the proportioning pumps is erratic. 4
Difference of pressure or speed in the up stroke against the down stroke. 5
SOLUTIONS
1. Loss in the Ball Checks
Check the pressure gauges to identify which pump is not maintaining pressure. To determine
which ball valve is failing, check in which displacement direction the pump is losing pressure. If
pressure is lost in an ascending direction, check the discharge ball valve (upper valve), if
pressure is lost in a descending direction, check the aspiration ball valve (lower valve).
Proceed as follows to check the ball checks:
a) Disconnect the machine from the pneumatic supply and close all supply valves and the
supply system to the hoses products.
b) Depressurise the proportioning pump and remove the corresponding ball check.
c) The loss from the ball checks is usually caused by foreign particles that prevent the
perfect coupling of the ball in the housing at the top of the closing bushing. Clean the
ball and the seat of the bushing and make sure there are no faults from nicks, marks or
scratches to the bushing or the ball. If cleaning fails to resolve the problem or any fault
is observed, replace the bushing and the ball.
2. Unbalanced Pressures
Pressures are unbalanced when there is an obstruction in the hose or in the gun that prevents
one of the components from leaving freely through the gun chamber when it is projected, or
when a problem in the pumping system prevents one of the components reaching the gun in the
required amount.
To identify which component is relatively easy if we bear in mind that the chemical components
used in the polyurethane foaming are of a different color. By observing the color of the material
that leaves the gun, we can determine which component is missing.