WIKA DELTA-comb 702.03.100 Betriebsanleitung Seite 14

6. Commissioning, operation
GB
6.3 Switch point setting and zero point test
The switch points are set at the factory when the set points are given.
The adjustment of the switch point is made by the adjustment screws accessible
from the front. An assistant scale over 270 ∢° enables a relatively accurate
adjustment of the switch points and indicates the set point that is currently
adjusted.
For contact adjustment, the vent plugs in the snap-in disc should be removed. By
turning the contact adjustment screws using a screwdriver the desired switch point
can be set.
If an even more accurate switch point setting is required, a reference standard
should be used for the adjustment.
Afterwards, the vent plugs should be pressed back into the snap-in disc.
Following the setting and the testing of the switch point in the equipment, the
instrument must be sealed and the set value marked on the instrument.
Zero point test
By opening a pressure compensating valve (see point 7.1 on page 15) a zero
point check during the running process is possible.
The medium flows from the higher-pressure side towards the opposite side and
the differential pressure at the gauge drops to zero.
By opening the pressure compensating valve, the differential pressure indicator
must drop to zero, i.e. into the area of the zero-point tolerance bar. The instrument
function is thus in order. With possible deviations, which are outside the tolerance
bar, a zero adjustment can be made using the standard built-in adjustable pointer.
To do this the snap-in disc should be lifted off,
using a screwdriver in the appropriate impression/
recess.
The zero adjustment is achieved by turning the
slotted screw on the adjustable pointer.
Afterwards, the snap-in disc should replaced on
the case.
The differential pressure will be displayed again
as soon as the pressure compensating valve is
closed once more.
14
Information
For the safety circuit, which will switch off the heating if the
steam generator falls below the minimum flow, only the normally
open contact of the changeover switch should be connected (i.e.
with Δp = 0 open circuit)!
WIKA operating instructions differential pressure gauge, model 702.03.100
Slotted screw