Van Air Systems Zero Loss Pneumatic PDV Series Drain Valves - Manual (Page 2)

IN GENERAL
In order for the condensate to properly enter the PDV-500 reservoir, the
condensate line to the PDV-500 must always be installed below the bottom of
the vessel to be drained. It is equally important to provide a means for the air
that is contained in the reservoir to escape (vent) as the condensate enters
the reservoir. If the air can not escape, the condensate will not enter the
reservoir. Below are suggestions on how to best install the PDV-500 on
typical types of vessels that have to drained of condensate. However, it is
possible to install the PDV-500 without a balance line (Dwg. not shown),
providing the condensate enters the top inlet and the flow rates are less than
9 GPH (750 cfm for an aftercooler or 1500 cfm drier) for a 1/2" drain line and
19 GPH (1500 cfm for an aftercooler or 3000 cfm drier) for a 3/4" line. The
use of unions and shut-off valves are recommended for both the condensate
line and the balance line.
RECEIVER TANK
The preferred installation for a PDV-500 on a receiver tank is having the
condensate enter the top inlet port and having the balance line go back to the
tank at a position that is above the level of the condensate (Dwg. 1).
FILTER and AFTERCOOLER MOISTURE SEPARATOR
If a cyclone separator or filter has pipe plugs located in the top of the head,
the plug closest to the discharge pipe should be removed and the balance
line should be installed (Dwg. 2). If there is no provision on the cyclone
separator or filter for a balance line, install it in the discharge side of the pipe
line and as close to the cyclone separator as possible.
REFRIGERATED DRYER
If a balance line is required, it must be connected to the port located on top of
the separator that is closest to the discharge side (Dwg. 2), or between the
separator and the air-to-air heat exchanger. If a port is not available as
described above, then venting to atmosphere is recommended. When venting
to atmosphere, the condensate should enter through the bottom entry port on
the drain. The bleed or needle valve is installed on the 1/8" NPT vent port and
allows the air in the PDV-500 reservoir to escape to the atmosphere (Dwg 3).
The bleed valve (not included) should be adjusted so that only 3 to 5 bubbles
per second are visible. We do not recommend installing a vent line down
stream from the dryer. The vent line can be a conduit for transferring moisture
from the drain to the previously dried air. This can result in unwanted moisture
being sent down stream.
INTERCOOLERS
Install the condensate drain line into the upper port only. This will prevent the
possibility of condensate being drawn back into the intercooler on some
systems. It is important that the vent line be installed on the same stage that
is being drained or to atmosphere.
BALANCE LINE
As mentioned above, both the use and the placement of a balance line is very
important. Most drain failures are the result of an improper balance line
installation. The balance line should be 1/4" tubing or larger, and installed on
top of a pipe or vessel, not the bottom. A needle valve is recommended for
controlling the air flow. Avoid having any loops or low areas in the balance
line that might allow moisture to collect in the line and prevent the passage of
air from the drains reservoir.
Dwg. 1
Dwg. 3
Dwg. 2
Needle Valve
1/8 npt
(Not Supplied)
Discharge
Port 1/2" npt
Control Line
Inlet Filter
Vent Line
Venting to
Atmosphere With
Needle Valve
(Not Supplied)
Needle Valve
1/8 npt
(Not Supplied)
Clean Dry Control
Air, 80 to 120psi
Control Line
Inlet Filter
Clean Dry Control
Air, 80 to 120psi
Clean Dry Control
Air, 80 to 120psi
Control Line
Inlet Filter
Discharge Port
1/2" npt
Discharge Port
1/2" npt
Vent Line
32-0277-A 2/09