GF Signet 2764-2767 Differential DryLoc pH_ORP Electrodes - Manual (Page 5)

5 Signet 275X, 276X, 277X Series pH and ORP Electrodes
5. Maintenance and Cleaning
5.1 Maintenance
Variables can affect long-term pH or ORP electrode life. For this reason, a maintenance log is recommended for trend analysis. When
storing boxed sensors, lay the sensor fl at to maximize hydration of the glass surface. Keep the glass surface wet at all times. Soak the
sensor tip in pH 4.0 buffer during system maintenance intervals. In-line applications should be plumbed with a depression (trap) so liquid
is maintained around the sensor tip. If the sensor dehydrates, soak the sensor tip in pH 4 buffer for 24 to 48 hours, then visually inspect
the electrode for surface cracks, swelling, or discoloration. Severely dehydrated electrodes cannot be restored to normal operation.
5.2 Cleaning
Cleaning techniques vary depending on the type of coating present on the glass electrode surface or reference junction.
• Soak electrodes in pH 4 buffer or KCl solution after cleaning.
• Soft coatings can be removed by vigorous stirring, or with directed spray of an applicable detergent or solvent onto the glass surface.
Chlorine bleach or mild detergent can be used to remove soft coatings. Always rinse electrode tip in clean water after cleaning.
• Hard coatings can be chemically removed. Use the least harsh chemical which will remove the contaminant within two (2) minutes
without attacking the materials of construction. e.g. calcium carbonate may be removed with a 5% HCl (muriatic acid) solution.
• Oily or organic coatings can be removed with detergents or an appropriate solvent that does not attack the materials of construction;
e.g. isopropyl alcohol may be used but acetone must be avoided to prevent damage to the CPVC sensor body.
• ORP platinum electrode surfaces can be gently wiped with a wet paper towel. More stubborn coatings can be removed by gently
sanding with 600 grit wet and dry silicone or carbide sandpaper, jewelers rouge, crocus cloth, or very fi ne steel wool.
5.3 276X Series Differential Electrodes
Differential electrodes have a replaceable salt bridge and the
electrolyte chamber can be refi lled. The electrolyte chamber
should be full. If any fl uid is audible when shaken, the chamber
should be refi lled. Refi ll the electrolyte chamber when the
electrode offset exceeds 50 mV. Replace the salt bridge when
performance becomes sluggish or if the output is erratic or
inaccurate.
Replacing the Salt Bridge
Parts Required: Salt Bridge (order number 3864-0001) and
Differential
Reference Solution
(order number 3864-0002)
Tools Required: Small pliers
Procedure:
1. Remove sensor from mounting.
2. Hold upside down and unscrew salt bridge using a pair of small
pliers. Be careful not to damage the glass bulb!
3. Drain the depleted reference solution and dispose of properly.
4. Fill reference chamber with fresh reference solution (approx.
30 ml).
5. Replace salt bridge and screw fi nger tight. Solution will drip out
while screwing in salt bridge.
Use pliers to turn approximately ¼ turn past fi nger-tight.
6. Perform calibration (standard and slope) before returning the
system to service.
WARNING!
Wear appropriate eye, face, hand, body, and
respiratory protection when using chemicals or
solvents. NOTE:
The refi llable electrolyte chamber in 276X series
differential electrodes may leak during storage and
shipping. Check the fl uid and refi ll before installation
if necessary.