Sensor Electronics SEC 3000, Instruction And Operation Manual

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Doc#: 1460003, Rev A Operation Manual, SEC 3000 Electro-Chemical Gas Sensor Page 6 of 13
III. OPERATION
Installation and Startup
Warning: The user shall be made aware that if the equipment is used in a manner not specified by the
manufacturer, the protection provided by the equipment may be impaired.
The first step in the installation process is to establish a mounting location for the SEC 3000. Select a
location that is typical of the atmosphere to be monitored or close to the anticipated source of a dangerous
gas.
It is very important that the SEC 3000 be properly located to enable it to provide maximum protection. The
most effective number and placement of sensors vary depending on the conditions of the application. When
determining where to locate sensors the following factors should be considered.

What are the characteristics of the gas that is to be detected? Is it lighter or heavier than air? If it is
lighter than air the sensor should be placed above the potential gas leak. Place the sensor close to the
floor for gases that are heavier than air or for vapors resulting from liquid spills. Note that air currents
can cause a gas that is heavier than air to rise. In addition, if the temperature of the gas is hotter than
ambient air or mixed with gases that are lighter than air, it could also rise.

How rapidly will the gas diffuse into the ambient air? Select a location for the sensor that is close to the
anticipated source of a gas leak.

Wind or ventilation characteristics of the immediate area must also be considered. Movement of air may
cause gas to accumulate more heavily in one area than in another. The detector should be placed in the
areas where the most concentrated accumulation of gas is anticipated. For outdoor applications with
strong wind conditions, it may require the sensors to be mounted closer together and on the down wind
side, to the anticipated area of a gas leak. Also take into consideration for indoor applications, the fact
that many ventilation systems do not operate continuously.

The sensor should be accessible for maintenance.

Excessive heat or vibration can cause premature failure of any electronic device and should be avoided
if possible.

Follow all national and local installation codes and practices
.
The SEC 3000 has a ¾” NPT threaded connector for mounting the detector to a junction box. SEC can
provide a junction box with terminals for this purpose.
A user-supplied junction box can be used providing it has the appropriate sized NPT conduit entries. The
junction box must be suitable for use in the application and location in which it is being installed. After the
device has been installed, a calibration is required. Refer to the Calibration section of this manual.
Wiring connections
Red wire: 8 to 32 VDC
Black wire: DC Common
Blue wire:
4 to 20 mA output
White wire: Smart Calibration Wire (data wire)
Earth Ground: Two (2) grounding screws on SEC 3000 housing.
Wire sizing:
0 to 500 feet, recommended wire gauge size 16 AWG
501 to 1000 feet, recommended wire gauge size 14 AWG