KROHNE OPTISENS PAS 2000 EN - Manual (Page 28)

6
SERVICE
28
OPTISENS PAS 2000
www.krohne.com 11/2008 • MA PAS 2000 R04 en
6.1.3 Incorrect measurements
6.1.4 Cleaning of the flushing nozzle
If the flushing nozzle becomes plugged, it can usually be cleaned by back flushing it with clean
water. Before attempting to backflush, close the valve for the flush water source and disconnect
the sensor flushing hose from the solenoid valve. Then, place a 12 mm hose over the flush
nozzle and carefully open the water valve.
The pressure should clear the line of solids. If backflushing does not work initially, try cleaning
the flushing nozzle with a needle. Try backflushing the nozzle again as described above until
clean water comes out at the solenoid valve end of the hose.
6.2 Cleaning
The sensor is equipped with a flushing nozzle. The nozzle is used to direct the cleaning liquid
supplied through a 6 mm hose that is mounted along the sensor housing to flush the electrode. A
solenoid valve that is wired to a relay in the MAC 080 converter controls the air or liquid (see
handbook OPTISENS MAC 080).
Compressed air is recommended for most applications.
Problem Solution
Dirty electrode Clean with distilled water
Insufficient or poor reference solution in the
electrode Refill/change reference solution (only for refillable
electrodes)
Change of "slope" due to age Recalibration
Old electrode which gives slope <93 % Change electrode
CAUTION!
For PAS 2000 submersible sensor the highest allowed flushing pressure is 6 bar / 87 psi. When
using air, 2 bar / 29 psi is usually sufficient.
NOTE!
Pay attention to the requirements for protection against backflow, according to the
EN 1717 standard for drinking water devices. If possible, use plant reuse water or effluent water
for cleaning.
.book Page 28 Friday, November 28, 2008 2:32 PM