4
6. Steam valves should be installed at each
ejector stage with pressure-tap openings
for attachment of pressure gauges when
required. Pressure readings must be
between the valve and the steam inlet.
7. Discharge piping must permit free flow of
exhaust vapors to prevent back pressure
from exceeding 32 in. (813 mm) hg. absolute
and the ejector discharge connection and
design flow conditions.
WARNING
Ejector exhaust must be piped to atmosphere in
a safe place due to the nature of the gases being
pumped. If exhaust is not piped to a safe place
properly, it could cause severe physical injury or
property damage.
Discharge silencers can be applied by the
user when desired and when sized properly
for pressure drop. If ejectors are discharged
vertically upward to atmosphere, a discharge
trap as shown in Figure 3 should be provided.
Intermediate ejector-stage-discharge piping
must be as short as possible and limited to not
more than one 90°bend. Other arrangements
are possible, but are not recommended without
factory approval of the proposed arrangement
to evaluate pressure loss.
Piping size equal to
ejector discharge size
or larger
Ejector
discharge
Drain line
Motive
steam
Drain leg
FIGURE 3
Discharge to
atmosphere
¼ drain valve
Suction
8. Care must be taken to insure leak-tight
ejector suction piping connections. Ejector
can be connected directly to the system
from which gases and vapors are being
pumped, however, it is recommended that
an isolating valve be provided between the
ejector suction connection and the system.
Operating problems on new processes
will be easier to diagnose and ejector
performance will be checked more easily
if an isolating valve is installed. Leak-tight
gate or butterfly valves are most suitable for
this application.
9. Eliminate or drain possible points of
condensate collection adequately to prevent
freezing.
10. Insulate all steam lines.
11. Do not impose system piping stresses upon
the ejector.
12. Allow clearance for removal of ejector.
5 OPERATION
5.1 Pre-operational check
1. Ensure that all installation procedures have
been completed.
2. Check to determine that all connections are
pressure tight.
5.2 Hydrostatic or vacuum test
1. Take all the precautions necessary to
handle the possibility of leakage during the
test.
2. Hydrostatic pressure test to 100 psig
(690 kPaG) or vacuum test and correct any
leakage before proceeding.
5.3 Operating
Note:
Steam-jet ejectors are devices using the
energy of the high velocity steam jet as it is
reduced in pressure from steam-inlet pressure
and expanded to suction pressure to entrain
and compress suction gases and vapors from
their inlet-pressure condition to a discharge
pressure that may be 10 or more times greater
than suction-inlet pressure for each individual
stage. Ejector stages are connected in series to
increase total system-compression range and
permit pumping gases and vapors from as low
as 0.25 in. (6.4 mm) hg. absolute pressure to
atmospheric discharge pressure.
1. Single stage ejectors
a. The first step in placing a single stage
model U or L ejector into operation is to
apply steam at the design pressure to the
nozzle.
b. The second step is waiting a period of time
to heat up and clear the steam lines and
ejector of all condensate. At this time,
the ejector should meet its guaranteed
performance.
2. Two stage ejectors
a. The first step in the start up of the two stage
model 2NC ejector system, particularly for
evacuation service, that is, reducing the
pressure within a closed space to some
predetermined value, is to place the Z stage
in operation by admitting design pressure
steam to the Z stage steam inlet.
b. The second step is to admit design steam
pressure to the Y stage steam inlet after the
vacuum system pressure has been reduced
to 10 to 8 inches (254 to 203 mm) of mercury
absolute.
c. After a period of operation sufficiently
long to heat up and clear the steam lines
and ejectors of all condensate, the ejector
system should meet its guaranteed
performance.
PENBERTHY
MODELS U, L AND 2NC FABRICATED METAL CONSTRUCTION JET PUMPS
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
