SECTION 4
®SULLAIR®
26
3700 Operator’s Manual and Parts List
OUTDOOR INSTALLATION (SHELTERED)
Many times a compressor must be installed outside due
to available space or other jobsite conditions. When this
is necessary, there are certain items that should be
incorporated into the system to help ensure trouble-free
operation. The unit must be purchased with a TEFC
motor. The standard machine has NEMA4 rated
controls, which are watertight.
The compressor should be on a concrete pad, which is
designed to drain water away from it. If the concrete pad
is sloped, then the compressor must be mounted so that
it is level. The base or skid must be sealed where it
contacts the concrete pad.
A weatherhood option should be selected to prevent
direct rain and snow from falling on the unit. If local
weather conditions can be extreme such that direct rain
or snow may fall on the unit, it should be in a fully
enclosed room or building.
If installed under a shelter, air-cooled machines must be
positioned in a way that prevents air recirculation (i.e.,
hot exhaust being allowed back to the system air inlet).
In installations that include more than one compressor,
hot air exhaust should not be directed toward the fresh
air intake of the second unit or an air dryer.
A standard machine installed outside must not be
started or run if the ambient temperature in and around
the compressor drops or may drop below 35°F (1.7°C).
For installation in a below freezing climate, a low
ambient option with heat tracing and a sump heater must
be installed.
4.3 SERVICE AIR PIPING
Review carefully the total air system before installing a
new compressor. Items to consider for the total air
system include liquid carryover, pipe sizing, and the use
of an auxiliary receiver. The installation of a drip leg or
multiple drip legs, installation of a line filter(s) and the
installation of isolation valve or valves. These
considerations are important to ensure a safe and
effective system.
PIPE SIZING
Pipe should be sized at least as large as the discharge
connection of the compressor. Piping and fittings should
all be suitably rated for the discharge pressure.
USE OF AUXILIARY RECEIVER / SUMP
An auxiliary receiver/sump should be used in cases
where large demand swings are expected. This is not
necessary with a variable speed design.
ISOLATION VALVE(S)
If isolation of the compressor from the service lines is
required, isolation valves should be installed close to the
discharge of the compressor. They should be installed
with drip legs that drain sloping downward from the base
in order to drain properly. Install a vent to the piping
downstream of the minimum pressure check valve on
the separator tank, and upstream of the first isolation
valve.
When two compressors are operated in parallel, provide
an isolation valve and a drain trap for each compressor
before the common receiver.
A built-in after-cooler reduces the discharge air
temperature below the dew point. For most ambient
conditions, considerable water vapor is condensed. To
remove the condensation, each compressor with built-in
after-cooler is supplied with a combination condensate
separator/trap. A drain line should be installed on the
condensate drain.
NOTE
Variable speed drive compressors are
NEMA 12 rated and must not be installed
outside or exposed to the elements.
SU_0000041
NOTE
Discharged air contains a very small
amount of compressor lubricating oil, and
care should be taken to ensure that this
oil would not interfere with downstream
equipment. An air dryer can remove any
liquid carryover.
SU_0000030
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