PMT200B SERIES DryLine
®
DEHYDRATOR USER MANUAL
4
This manual contains the information you need
to install, operate and maintain your PMT200B
Series DryLine
®
dehydrator. Please take the time
to read this manual before attempting to operate
or service the unit.
This appliance is not intended for access by
the general public.
This appliance is not intended for use by
persons (including children) with reduced
physical, sensory or mental capabilities,
or lack of experience and knowledge,
unless they have been given supervision or
instruction concerning use of the appliance
by a person responsible for their safety.
PMT200B Series DryLine
®
dehydrators provide
dry air for pressurizing small (up to 1700 liters
(60 ft
3
), in volume) antenna and transmission
line systems. The dehydrators produce –45º C
(–50º F) dewpoint dry air at an output rate of 5.7
SLPM (0.2 SCFM).
Each dehydrator consists of an electrically-
driven air compressor, a membrane dryer
assembly, an automatic transmission line
pressure sensing system and alarm outputs
housed in a rigid metal chassis. It is designed to
mount directly to the wall or as a free-standing
unit. The front panel features a control interface
with display for alarms and pressure. For
easy serviceability, power connections, alarm
output connections and all filter elements are
accessible from the top or front of the unit.
The PMT200B maintains transmission line
pressures at 21 kPa (3.0 psig). It is intended
for standard microwave antenna applications
and any other transmission line pressurization
requirement that supports a medium pressure
limit. The output pressure is adjustable from
13.8 kPa (2.0 psig) to 41.4 kPa (6.0 psig).
PMT200B Theory of operation.
The PMT200B series of DryLine
®
dehydrators,
while similar in moisture removal technology,
operates differently than some of the
DryLine
®
series of dehydrators
. In order to
provide a constant supply of dry air to small air
volume systems, and to maintain an acceptable
dryness level in the product air stream, a high-
pressure reservoir tank is utilized. This reservoir
tank is connected to a pressure regulator and
orifice to yield a fixed output pressure of 21
kPa (3.0 psig) and a nominal flow rate of 5.7
SLPM (0.2 SCFM). In addition to supplying
the output air, the reservoir tank also provides
the dry air for the feedback loop. The feedback
loop is necessary to maintain the dryness of the
membrane cartridge.
During normal operation, the bleed air in the
feedback loop will cause the pressure to slowly
drop in the internal reservoir tank, and the
PMT200B compressor will cycle automatically.
These cycles will take place regardless of the
system volume or condition of the transmission
line the dehydrator is connected to. The rate of
these cycles, however, will vary.
When connected to a very tight system, or
the output is capped, the dehydrator will cycle
approximately every 60 minutes and maintain
21 kPa (3.0 psig) system pressure. When
open to atmosphere, the dehydrator will
cycle approximately every 3 minutes while
providing close to 5.7 SLPM (0.2 SCFM) of
dry air. A system that leaks will have a cycle
time somewhere in between, depending on the
severity of the leaks.
The display will also reflect a pressure between
0 and 21 kPa (3.0 psig) while the output flow
is between 0 and 5.7 SLPM (0.2 SCFM). The
pressure sensor tracks the pressure beyond
the flow control orifice and will show the actual
pressure in the transmission lines (or to the
distribution manifold).
