8
INITIAL STARTUP PROCEDURE
1. Vacuum Switch Settings:
a. On simplex systems used in conjunction with a vacuum receiver tank of proper size set one pointer to
maximum vacuum required (do not exceed 28” Hg vacuum [-95 kPa g] for water sealant, or 29” Hg vacuum
[-98 kPa g] for oil sealant). Then, set the other pointer to the minimum vacuum required. This will cause the
pump to evacuate the receiver tank until the maximum vacuum set point is reached and then shut down.
When the vacuum in the receiver tank drops to the minimum vacuum setting, the pump will then start and
increase the vacuum in the receiver to the higher point.
NOTE:
The pump motor should not be started more than five (5) times per hour to avoid overheating. If the
vacuum usage is great enough on the receiver to cause the pump to restart more frequently, then
either a larger receiver volume should be selected, a duplex system should be used, or a minimum
run timer should be installed in the motor control center to limit the number of starts to five (5) per
hour. For systems equipped with a control panel, (standard on DRSP/DRDP, optional on ACRP/
OFRP) minimum run timers are installed to prevent more than five (5) starts per hour. The pump(s)
will continue to run until the timer expires, or the vacuum set point is reached, whichever occurs
last.
b. On simplex systems without a receiver tank, the pump is normally operated continuously by turning the H-
O-A selector switch to H (“Hand“ setting), which bypasses the vacuum switch.
c. On duplex systems, two (2) vacuum switches are provided as well as an alternator. Switch #1 is used for
the standard vacuum range (High-Low) to be maintained on the receiver tank as explained in 1a) by each
pump (one [1] switch per pump). For example, switch #1 may have a high setting of 28” Hg vacuum [-95
kPa g] and a low of 26” Hg vacuum [-88 kPa g]. If the vacuum level in the receiver drops to 26” Hg [-88 kPa
g] vacuum, pump “A” will start to bring the level back to 28” Hg vacuum [-95 kPa g]. On the next start, the
alternator will select pump “B” to evacuate the receiver. Subsequent cycles will start pump “A”, then pump
“B”.
Switch #2 is used to set a minimum vacuum level where both pumps will start to bring the vacuum level
back to the high setting shown on switch #1. On switch #2 the low vacuum setting is the significant set
point. Set the lower pointer to this point. The higher pointer may be set at any value between the maximum
setting on switch #1 and the low setting on switch #2. For example, if switch #1 is set at 28” and 26” Hg
Vac and switch #2 is set at 26” and 24” Hg Vac, then if the vacuum level drops to 24” Hg Vac or less, both
pumps will continue to operate until the vacuum is returned to the high setting on switch #1, 28” Hg Vac
where both will shut down. See also Figure 1 on the facing page.
NOTE:
On duplex systems with 50 HP motors or larger, a timer is incorporated to delay starting of the
second pump by a few seconds to prevent excessive current draw if both started together.
d. On a duplex system used without a receiver tank the pumps are normally operated in the manual mode by
turning the H-O-A selector switch to H (Hand).
2. Turn on main power by turning fusible disconnect switches to “ON”
3. For initial check out, turn H-O-A selector switch to H. On duplex systems, start each pump separately.
4. Crack inlet isolation valve of the pump to be started.
5. Push start button for that pump.
6. Open cooling water valve to the heat exchanger.
7. Adjust the vacuum relief valve if necessary to prevent cavitation of the pump and still obtain the vacuum level
required. Check the functioning of this valve with the main inlet isolation valve closed. The pump should not
cavitate.
When cavitation occurs, the pump sounds as though it has gravel in it. This noise will commonly
occur when the pressure is low and the air or non-condensable gas flow is slight. Cavitation should
be reduced or eliminated by bleeding air into the pump through the attenuation valve. If enough air
can not be bled into the pump to satisfactorily quiet the pump, an air bleed valve should be installed.
Non-condensable gas may be recirculated by adding a return line from the discharge separator tank
to the pump inlet bleed valve.
On oil sealed systems, a maximum vacuum level of 29” Hg vacuum [-95 kPa g] should be possible without
cavitation and on water filled systems (assuming 60° F [15° C] cooling water) 28” Hg
vacuum [-95 kPa g] should be possible without cavitation. Higher water temperatures will result in cavitation at
lower vacuum.