Detcon DM-700 - Manual (Page 11)

Model DM-700
DM-700 Instruction Manual Rev. 4.0 Page 7 of 48
Additional Placement Considerations
The sensor should not be positioned where it may be sprayed or coated with surface contaminating substances.
Painting sensor assemblies is prohibited.
Although the sensor is designed to be RFI resistant, it should not be mounted in close proximity to high-
powered radio transmitters or similar RFI generating equipment.
Mount in an area void of high wind, accumulating dust, rain or splashing from hose spray, direct steam
releases, and continuous vibration. If the sensor cannot be mounted away from these conditions then make
sure the Detcon Harsh Environment Splashguard accessory is used.
Do not mount in locations where temperatures will exceed the operating temperature limits of the sensor.
Where direct sunlight leads to exceeding the high temperature-operating limit, use a sunshade to help reduce
temperature.
2.3 Sensor Contaminants and Interference
Electrochemical toxic gas may be adversely affected by exposure to other airborne gasses. Depending on the
cross-sensitivity relationship, there may be a positive or negative impact on the reading.
The most commonly present gasses that potentially cause interference problems are listed in Table 6 Cross
Interference Table (refer to Section 9).
The presence of cross-interference gasses in an area does not preclude the use of this sensor technology,
although it is possible that the sensor could experience a false high or false low reading should exposure occur.
Cross-Interference Data Table
Table 6 Cross Interference Table (refer to Section 9) lists the gasses typically found in industrial environments
that may cause a cross-interference response on members of the Detcon family of toxic gas sensors. Review
Table 6 in Section 9 for the correct gas and then scan across the list for possible interference gasses.
Determine the magnitude of cross-interference that may occur.
2.4 Mounting Installation
The DM-700 sensor assembly is designed to be threaded into a ¾” Female NPT fitting of a standard cast
metal, Explosion-Proof Enclosure or Junction Box. There are two wrench flats on the upper section of the
sensor that should be used to thread the sensor into the ¾” female NPT receiving connection. Thread the
sensor up until tight (5 turns is typically expected) and until the display is pointed in the direction that sensor
will normally be viewed and accessed.
The DM-700 should be vertically oriented so that the sensor points straight down. The explosion-proof
enclosure or junction box would then typically be mounted on a wall or pole. Detcon provides a standard
selection of junction boxes available as sensor accessories (See Figure 8 below). Any appropriately rated
enclosure with a downward facing ¾” NPT female connection will suffice.
When mounting on a wall, it is recommended to use a 0.25”-0.5” spacer underneath the mounting ears of the
Detcon standard J-Box to offset the sensor assembly from the wall and create open access around the sensor
assembly. Spacing requirements for other junction boxes may vary.