28 3600 Analyzer for O
2
Measurement—Operator’s Manual
3600O2.OM.E9903
1.5 Maintenance (Sensor Service)
Normally only the sensor requires service. If the indicating instrument is properly
connected, handled with reasonable care and kept clean, it should give you no
mechanical or electrical problems.
For the sensor, membrane wear and chemical reactions require that a specific
maintenance procedure should be performed from time to time. We cannot dictate
a specific maintenance schedule for your application, since operating conditions
vary considerably. However, experience should make the intervals apparent, using
the guidelines below.
Locate the cylindrical, black plastic base that is supplied with the sensor. The base
screws into the sensor at the bottom, placing the sensor in a secure, upright
position and using an O-ring to seal the LEMO-10 connector from moisture. (Or,
your Orbisphere representative may have supplied a larger, two-piece black plastic
stand, model M26-5500, also designed for this purpose.)
The sensor service procedure is as follows (you may also refer to the Orbisphere
poster “The ABC of Sensor Service” for further illustration of this procedure).
1.5.1 When to Perform a Sensor Service
You will know it is time when you experience:
• difficulties with calibration,
• an unusually long stabilization time, either with the sensor exposed to an air-
saturated medium or to changing oxygen concentration conditions, or
• “noisy” or drifting signals under what you believe to be constant oxygen
concentration conditions.
1.5.2 Remove Sensor from Sample
When you remove a sensor from either a flow chamber or sensor socket, take care
that no hazard will be created by the absence of the sensor. (In particular, when
using a sensor socket to measure in liquid samples, make sure to drain all liquid
from the pipe.)
Remove the sensor cable by unscrewing the LEMO connector at the end of the
sensor handle. Then hold the sensor handle in one hand, and carefully unscrew the
collar and pull the sensor out of its socket or out of the flow chamber.
Place the sensor in its plastic base, screwing it down securely but not tight enough
to strip the plastic threads. An O-ring in the base provides a watertight seal for the
LEMO-10 connector of the sensor.
1.5.3 Prepare Sensor for Cleaning
Carefully unscrew the protection cap, using the metal
tool supplied with your recharge kit. Take care not to
lose the grill and washers inside. The protection cap
includes washers, and for some applications, a Dacron
mesh and a stainless steel grill—if you are unfamiliar
with these components, check the exploded sensor
diagram in section 1.6.1.
You may want to check back to the sensor diagram in
section 1.2, and note the order of sensor head
components shown:
• Membrane holding ring;
• Membrane; and
• The sensor’s membrane support.
Removing
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