5
CD-20SFA Sample Probe Controller
Section 1—Overview
The CD-20SFA Sample Probe Controller is engineered to provide pulse input (ow proportional) control
of the True-Cut C-Series sample probe. When a “start” pulse is received, the probe is rotated to capture and
discharge an isokinetic sample. When installed in a horizontal line, the probe is stopped in the closed position,
while on a vertical line the probe is stopped in the open position.
The C21 probe collects one 1.5 cc sample per 360-degree rotation.
The C22 probe collects two 1.5 cc samples per 360-degree rotation.
A failure alarm relay provides an output to alert users to a loss of power, loss of input signal, or motor failure.
The relay contact remains open (inactive) for as long as a sample is being taken within the alarm delay period
congured with the control card potentiometer. Alarm delays can range from 5 seconds to 6 minutes.
An explosion-proof housing encloses the complete assembly, and two ¾-in. NPT holes allow connection of
the line power and input pulse (for ow-proportional sampling). A ½-in. breather plug and a ½-in. conduit
plug are installed on opposite sides of the enclosure.
A coupling, jam nut, and hub allow the assembly to be mounted directly to the C-Series sample probe. No
brackets or supports are required; however, they are recommended for piping with signicant vibration.
The CD-20SFA controller consists of the following:
• a motor control assembly (24VDC, 115VAC, or 230VAC)
• a DC gear motor with a gear ratio of 150:1
• a cam with two high points mounted on the gear motor output shaft
• a proximity switch mounted in the hub assembly opposite the cam
When a high point on the cam is opposite the proximity switch, the PROX (“Hold”) LED is illuminated. This
signal indicates the sample probe is at the “stop and hold” position.
Figure 1.1—CD-20SFA controller components
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