Hazardous Environment Wiring; Figure 3. Required Supply Voltage Vs. Loop Resistance - Universal Flow Monitors FlowStream OFS User Manual

Figure 3. Required Supply Voltage vs. Loop Resistance

Hazardous Environment Wiring

Intrinsically Safe wiring must be installed in accordance with Article 504 of NEC, ANSI NPF 70
and Control Drawing Number 7577, Revision 00 (Figure 4, below). The transmitter approval
by the Canadian Standards Association for installation in Hazardous environments is based on
installation through an Intrinsic Safety Barrier.
The Transmitter when wired through the I.S. Barrier is suitable for use in:
CLASS I GROUPS A, B, C & D
CLASS II GROUPS E, F & G
CLASS III HAZARDOUS LOCATIONS
Earth Ground of the I.S. Barrier must be connected to the earth ground of the AC feeder supply.
The resistance between Intrinsically Safe ground terminals and A.C. Earth ground must be less
than one Ohm. (UFM suggested I.S. Barrier R.Stahl 9001/01-280-075-10, UFM part number
8140).
The Power Supply voltage is limited to 24 VDC Max. The Power Supply Control Unit must not
use or be able to generate more than 250 volts. The Maximum Load that can be put on the
system is 250 Ohms.
All repairs on the Flow Transmitter should be accomplished at the factory because any
substitution of components may impair Intrinsic Safety.
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