Zamil PDS Series Installation, Operation & Maintenance Manual - page 23
All compressors are charged with somewhat greater than the normal oil level required for adequate lubrication, in order
to provide some allowance for oil which will be circulating in the system during operation. Depending on the system
design, the amount of oil in the system at the time of compressor installation, oil lost due to leakage, etc., it may be
necessary either to add or remove oil from a system any time it is first placed in operation with a different compressor.
An abnormally low oil level may result in a loss of lubrication; while an excessively high oil level may result in oil
slugging and possible damage to the compressor valves or excessive oil circulation. The oil level may vary consider-
ably on initial start-up if liquid refrigerant is present in the crankcase, and the oil level should be checked with the
compressor running after having reached a stabilized condition.
(d) Thermostatic expansion valves must be checked for proper superheat settings. Recommended superheat is 15
0
F
to 20
0
F.
(e) Using suitable instruments, carefully check line voltage and amperage at the compressor terminals. Voltage must
be within ±10% of that indicated on the compressor nameplate. If high or low voltage is indicated, notify the power
company. The current normally should not exceed 110% of the nameplate rating. If amperage draw is excessive,
immediately determine the cause and take corrective action. On three phase compressor motors, check to see
that a balanced load is drawn by each phase.
(f) Carry out any necessary tests, recording airflow rates, entering/leaving temperatures, sound levels, outdoor tem-
peratures, supply airflow rates in occupied spaces and any other specified parameters.
BELT TENSION TESTING PROCEDURE INSTRUCTION
To determine the lbs. force required to tension a drive, you simply do the following:
1. Measure the Belt span as shown.
2. Divide belt span by 64 to get belt deflection needed to check tension.
3. Set large "0" ring on span scale at required belt deflection. This scale is in 1/16" increments.
4. Set small "0" ring at zero on the "Force Scale" (plunger).
5. Place the larger end of the tension checker squarely on one belt at the center of the belt span. Apply force on the
plunger until the bottom of the large "0" ring is even with the top of the next belt or with the bottom of a straight edge
laid across the sheaves.
6. Read the force scale under the small "0" ring to determine force required to give the needed deflection.
7. Compare the force scale reading with the correct value for the belt style and cross section used, as given in table on
next page. The force should be between the minimum and maximum values shown.
8. If there is too little deflection force, the belts should be tightened. If there is too much defection force, the belts
should be loosened.
EXAMPLE
1. Belt Span 64" (Small Sheave is 3.0 P.D. with "A" type belt.
2. 64 = 1" Deflection needed.
3. Set large "0" ring at 1" on span scale.
4. Set small "0" ring at zero plunger.
5. Check the force – lbs. required for a 1" deflection of the belt.
6. Press down on plunger until the bottom of the large "0" ring is even with top of the next belt in the set or with the bottom
of a straight edge.
7. 'A' type belts table shows an "A" belt with 3.0" P.D. Small sheave should have a deflection force between 1-1/2 lbs.
and 2-1/8 lbs.
8. Increase or decrease the tension on belts until the deflection force is between 1-1/2 lbs. 2-1/8 lbs.
NOTE:
Tension new drives at the maximum deflection force recommended. Check the tension at least two times during the first
day's operation as there normally will be a rapid decrease in belt tension until belts have run in. Check the tension
periodically after the first day's operation and keep tension in recommended area. The correct operating tension for a
V-belt drive is the lowest tension at which the belts will not slip under the peak load conditions. Shafts must be adequate
for the tensions required.
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