Mounting The Sensing Unit; Piping Or Tubing Connections - Honeywell 7866 Operation And Maintenance Manual

Installation
Reference Gas
Provide a source of reference gas, if required. If hydrogen or helium, supply at 0.02 cfh to 0.2 cfh
(10 cc/min to 100 cc/min). Vent to atmospheric pressure. (If hydrogen, vent to a safe ventilating system.).
If flowing air is required, supply at 0.5 cfh to 2.0 cfh (250 cc/min to 1000 cc/min). Vent to atmospheric
pressure.
3.3

Mounting the Sensing Unit

Explosion-proof Housing
EXPLOSION-PROOF SENSING UNIT REQUIREMENTS
•
When measuring gas mixture that contains oxygen, the maximum oxygen concentration must not
exceed 21%.
•
Always use conduit for electrical wiring and seal all conduits within 18 inches.
•
Make certain fully qualified personnel make this installation and all local regulations are observed.
Failure to comply with these instructions could result in fire caused by explosion inside the housing.
The sensing unit is designed as explosion-proof. Dimensions for this unit are shown in Figure 3-1.
Electrical conduit must be used for all wiring and the openings are fitted for 1/2-inch conduit.
Mount the explosion-proof sensing unit in accordance with Figure 3-1.
3.4

Piping or Tubing Connections

Inlet and Outlet Connections
The O-ring type compression fittings in the base of the sensing unit will accept plastic or metal tubing
having an O.D. between 0.236 inches (6 mm) and 0.255 inches (6.5 mm). Make inlet and outlet
connections in accordance with Figure 3-1.
Types of Tubing
Any metal and most plastic tubing can be used provided it is chemically compatible with the sample gas.
Avoid the use of plasticized PVC or other soft tubing at the sensing-unit compression fittings and do not
use tubing having an inside diameter less than 4 mm.
Outlet Line Connection
To maintain the analyzer cell at constant pressure under various flow conditions, the outlet line must be
less than two meters (six feet) long and should exit to atmospheric pressure. No restrictions (other than a
Rotameter-type flowmeter) can be used in this line. If a longer vent line is required, use larger diameter
tubing, e.g., 12 mm (1/2") O.D. Refer to Appendix A for sampling and venting information.
20 7866 Triple Range Digital H and CO Analyzer/Indicator - Operation and Maintenance
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