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8. Operation
8.6.2
Minimum Op
erating Pressures
:
8.6.2.1
For 150 psig (1
0.5 kgf/
cm
2
) MOP models -
•
60 psig (4.2 kgf/cm
2
) is the minimum operating pressure
for dryers operated on a 4,10,16, or 24-minute cycle.
8.6.2.2
For 250 psig (1
7.6 kgf/
cm
2
) MOP models -
•
120 psig (8.44 kgf/cm
2
) is the minimum operating
pressure for dryers operated on a 4,10,16, or 24-minute
cycle.
Refer to Dryer Serial Number Tag.
WARNING - Do not operate the dryer at pressures below the
minimum operating pressure shown on the serial number tag.
NOTE: Consult factory for applications requiring lower minimum
operating pressures.
8.6.3
Maximum Co
mpressed Air
Temperatu
re at Dryer
Inlet:
•
140°F (60°C) for all models.
8.6.4
Amb
ient Temperatures
:
8.6.4.1
Mini
mum Ambient Temperature
:
•
Standard units: 35°F (2°C)
•
Units with optional low ambient package: -20°F ( -29°C)
8.6.4.2
Maximum Am
bient Temperature
:
•
120°F (49°C)
NOTE: If dryer is installed in ambients below 35°F (2°C), low
ambient protection requiring heat tracing and insulation of the
prefilter bowls, auto drains and/or sumps, and lower piping with
inlet switching and purge/repressurization valves is necessary
to prevent condensate from freezing. If installing heat tracing,
observe electrical class code requirements for type of duty
specified. Purge mufflers and their relief mechanisms must be
kept clear from snow and ice buildup that could prevent proper
discharge of compressed air.
8.7
Maximum I
nlet Flow Capacity
•
Refer to Table 8-1 for maximum inlet flow at rated
conditions of 100 psig (7.0 kgf/cm 2) and 100°F (38°C).
•
At other conditions, multiply inlet flow from Table 8-1 by the
multipliers from Tables 8-2 and 8-3 that correspond to the
pressure and temperature at the inlet to the dryer.
8.8
Purge and O
utlet Flows
8.8.1
Maximum Pur
ge Flow
•
Maximum Purge Flow is the amount of purge air flowing
through the off-stream tower when the
purge/repressurization valve is open. After the
purge/repressurization valve closes, the purge flow will
gradually decrease as the off-stream tower re-pressurizes
to line pressure.
•
For maximum purge flow multiply the Inlet Flow At Rated
Conditions from Table 8-1 by Maximum Purge Flow Factor
from Table 8-6 that corresponds to the dryer MOP, Cycle
Time Setting, and air pressure at inlet to dryer. Note: For
Level 2 Controller equipped dryers supplied with the
Automatic Purge Saving System operating in the
Demand Cycle Mode, use ISO Class 2 (10 minutes) as
the cycle time.
8.8.2
Average Purg
e Flow
•
For dryers with Level 1 or 2 Controllers operating in the
fixed cycle mode, the Average Purge Flow is the actual
amount of flow used during the entire
purge/repressurization cycle. It includes the maximum
purge flow for a portion of the purge/repressurization time
and the volume of air used for repressurization, averaged
over the cycle time.
•
For average purge flow multiply the Inlet Flow At Rated
Conditions
from
Table 8-1 by Average
Purge/Repressurization Flow Factor from Table 8-7 that
corresponds to the dryer MOP, Cycle Time Setting, Energy
(purge) Savings % setting, and air pressure at inlet to
dryer.
8.8.3
Minimum Out
let Air Flow
•
Determine minimum outlet flow available from dryer by
subtracting Maximum Purge Flow found above from inlet
flow to the dryer.
8.8.4
Average Out
let Air Flow
•
For dryers with Level 1 or 2 Controllers operating in the
fixed cycle mode, the average outlet flow available from
dryer can be determined by subtracting the Average
Maximum Purge Flow found above from the inlet flow to
the dryer.
8.9
EXAMP
LE
•
Find the maximum inlet flow, maximum purge flow, and
minimum outlet flow for a 60 SCFM unit with a MOP of
150 psig operated with 120 psig and 100°F inlet
conditions on a 10 minute cycle. Dryer will operate with
an inlet airflow of 46 SCFM.
•
Step 1: Find Maximum Inlet Flow at 120 psig by
multiplying Maximum Inlet Flow at Rated Conditions from
Table 8-1 by Inlet Pressure Correction Factor for 120 psig
from Table 8-2 and Inlet Temperature from Table 8-3:
60 x 1.08 x 1.00 =64.8 SCFM.
•
Step 2: Find Maximum Purge Flow by multiplying
Maximum Inlet Flow at Rated Conditions from Table 8-1
by Maximum Purge Flow Factor from Table 8-5:
60 x 0.162 =9.7 SCFM.
•
Step 3: Find Minimum Outlet Flow available by
subtracting Maximum Purge Flow (Step 2) from actual
inlet flow:
46 -9.7 =36.3 SCFM.
.
Содержание DGH Series
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