Page 5
BREAKDOWN OF VBA UNLOADER
25
23
24
22
21
20
19
18
17
16
15
14
13
12
15
12
9
10
11
Kits
SETTING UNLOADER VALVES
When setting unloaders, it must be carried out with the correctly
sized, new, nozzle in the gun.
The nozzle determines the maximum pressure that may be
obtained. If the nozzle is worn or too big to start with, the unloader
can be screwed right down without the correct pressure ever
being achieved. When it has been screwed too far down, however,
and the the gun is then closed, the pressure will go very high
before the unloader valve can dump. This will damage the pump
and probably even burn out the motor.
There are limiting sleeves available for fitting to the unloader
stem. They are for predetermined pressures and should be
fitted to prevent the over tightening of the knob.
It is important to check whether the gauge reads in bar or Mpa.
1Mpa = 10bar
The correct procedure for setting an unloader is:
·
Fit a gauge to the unloader port or to a tee plumbed after the
unloader valve in the hose line.
·
Unscrew the unloader knob until it is loose.
·
Switch on the pump motor.
·
Holding the gun open (with the correct new nozzle installed),
slowly screw down the unloader knob watching the gauge the
whole time. If the pressure ceases to rise before it has reached
the correct level, it means that the pump is not delivering the
correct volume or that the nozzle is worn or too large.
·
When the correct pressure is reached, or the indicated
pressure stops rising, close the gun and observe the pressure
on the gauge. It should only have risen about 10 to 20 bar
between the gun-open and gun-closed situations . If the
differential between the open and closed gun pressures is
greater than 20 bar, back off the unloader knob until the
differential is correct.
·
Check the amperage being drawn by the motor, with the gun
open. Make sure it does not exceed the motor manufacturer's
recommendation, usually stated on the motor label.
·
Lock the nut down on the top of the knob. Repeatedly open
and close the gun to verify that the higher and lower pressures
have the 20bar maximum differential, and that the motor is still
drawing the correct amps.
Pressure
Adjusting
Knob
Inlet from
Pump
By-pass
is internal
Outlet
to Gun
Mountings
(to pump
head)
Pos
Code
Description
Qty
1
1206.11
Stem
1
2
0009.18
Teflon Ring
1
3
0601.70
O-ring
2
4
1407.24
Connector
1
5
0601.62
O-ring
1
6
0009.19
Teflon Ring
1
7
0101.11
Guide bushing
1
8
0601.14
O-ring
1
9
4504.00
Ball Sub-assembly
1
10
1503.16
Seat
1
11
0601.41
O-ring
1
12
1408.02
Seal Washer 3/8
2
13
1800.04
Hollow Bolt 3/8
1
14
1800.07
Hollow Bolt 1/2
1
15
1408.03
Seal Washer 1/2
2
16
0204.83
Body Valve
1
17
1102.07
Poppet
1
18
0900.04
Spring
1
19
0601.19
O-ring
1
20
1407.25
Outlet Connector
1
21
1202.07
Plate
1
22
0900.31
Spring
1
23
1803.04
Set Screw
1
24
0302.09
Nut
1
25
0905.10
Brass Handle
1
1
3
4
2
5
6
7
8
3
Code Inc Pos
Description
Qty
2628.00
O-ring Repair Kit
2
0009.18
Teflon Ring
1
3
0601.70
O-ring
2
5
0601.62
O-ring
1
6
0009.19
Teflon Ring
1
8
0601.14
O-ring
1
11
0601.41
O-ring
1
19
0601.19
O-ring
1
2628.01
Outlet Kit
17
1102.07
Poppet
1
18
0900.04
Spring
1
19
0601.19
O-ring
1
2628.02
Stem Repair Kit
1
1206.11
Stem
1
9
4504.00
Ball Sub-assembly
1
10
1503.16
Seat
1
11
0601.41
O-ring
1
21
1202.07
Plate
1
22
0900.31
Spring
1
Spares
