Pneumatech PMNG Series, Installation, Operation & Maintenance Manual

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affect warranty. Instructions are given for adjustment in section 9, if for any reason the controller
must be replaced or re-adjusted.
4. On/Off Selector Switch – If the unit is supplied with heater and controls, (but no Operator
Interface), the panel will have an On/Off selector switch to start & stop the system. The unit will
requires pressure on the system before the heater will run. Systems with Operator Interface, have a
Power OFF/On switch.
5. SurePure™ Purity Vent – This is a system that will vent off-spec nitrogen to atmosphere until the
product gas meets the required purity. Unit is shipped factory set as called out in either the
purchase order or job specifications. If unit is supplied with the automatic purity vent the user can
adjust the HI Alarm (Alarm 1) on the oxygen analyzer to dictate when the generator is within
acceptable limits on delivered oxygen content. Simply, press the Mode button on the oxygen
analyzer and toggle until Alarm 1 appears. Press the [Up Arrow] or [Down Arrow] key until the
desired setting. Press the Mode button repeatedly until “Run” appears. In approximately 2 minutes,
the unit will go back to normal. The setting must be greater than the purity controller set point as
described in section 7.2, paragraph 2 above.
6. Main Flow Meter – Each unit is equipped with a nitrogen flow meter and on cabinet systems is
panel mounted.
7.
Economizer
– If the unit is supplied with this option, the system will also have a nitrogen storage
tank downstream of the generator unit. The purpose of this option is to save energy and run time on
the unit during times of low or no demand. There are high (PS2) and low (PS3) pressure switches
to be set. The low-pressure switch (PS3) should be set slightly above the minimum acceptable
pressure to allow at least 5 minutes of operation from storage. This can be calculated using the
following formulae.
MPs MP P
= + ∆
Where: MP = Minimum Pressure
MPs = Minimum Pressure Setting of PS3
∆
P = Pressure difference between MPs & MP
P
V
Storage
∆ =
×
7 . 14
Where: Storage = Rate x Minutes
14.7 = Atmospheric pressure (PSI)
Rate = Maximum demand flow rate in SCFM
SCFM = SCFH
÷
60
V
= Volume in Standard Cubic Feet (SCF)
SCF = Tank volume in gallons
÷
7.4805
Example:
You have a minimum pressure requirement of 40 PSIG, a 1060-gallon tank, and a maximum
demand of 450 SCFH. Calculate the minimum pressure setting.
1. Solve for SCFM (450
÷
60) = 7.5 SCFM
2. Solve for SCF (1060
÷
7.4805) = 141.7 SCF
3. Solve for Storage (7.5 SCFM x 5 minutes) = 37.5 SCF of Storage
4. Solve for
∆Ρ
PSID 9 . 3
7 . 141
7 . 14 5 . 37
=
×
5. Solve for MPS (40 PSIG + 3.9 PSID) = 43.9 PSIG minimum switch setting.
The low-pressure switch (PS3) should never be equal to or greater than the setting of high-pressure
switch (PS2). In fact, it should be at least 10 percent lower to avoid control problems due to drift of
the pressure switches.
The high-pressure switch (PS2) should be set at least 25 PSIG below the minimum required inlet
pressure to the unit to allow for pressure drop through the unit due to normal pressure drop and
filter particle buildup.