Specifications

FORM 160.80-NOM1

YORK INTERNATIONAL

OVERALL LEVEL OA 0.500 IN/SEC (0-PK)

MTR/MALE RTR RPM MTR 3570 RPM = 59.5 HZ

4/6 LOBE RATIO LR 0.67

FEMALE ROTOR IDLE 2380 RPM = 39.7 HZ

MALE ROTOR LOBES LOB 4

PUMPING FREQUENCY BPF 14280 CPM = 238.0 HZ

FREQUENCY MAX FMAX 178500 CPM = 2,975.0 HZ

SPECTRAL ALARM BANDS FOR 4/6 LOBE TWIN SCREW CHILLERS

Reference: Proven method for specifying spectral band alarm levels and frequencies using today’s predictive

maintenance software systems

James E. Berry, Technical Associates of Charlotte, Inc.

DESCRIPTION OF BAND COVERAGE

BAND 1 MOTOR/MALE RTR & FEMALE RTR RPM

BAND 2 2X - 3X MOTOR/MALE ROTOR

BAND 3 1X - 2X COMPR. PUMPING FREQUENCY

BAND 4 3X - 4X COMPR. PUMPING FREQUENCY

BAND 5 5X - 6X COMPR. PUMPING FREQUENCY

BAND 6 >6X COMPR. PUMPING FREQUENCY - FMAX.

NOTES:

1. Assume measurements by accelerometer or velocity pickup as close as possible to Bearing Housing, see Fig. 32.

2. Assume machine NOT mounted on vibration isolators (for isolated machinery - set alarm levels 50% higher).

3. Set motor levels same as compressor given above.

4. Chiller must be at a consistent condition (not only motor amps) when measurements are taken. Monitor and record all

performance parameters.

5. Aerodynamic noise (pressure pulsation) sources dominate mechanical sources at pumping frequency and harmonics

and does not represent energy transmitted through bearings.

6. Set danger levels 50% higher than alarm levels.

7. Another set of data with much higher Fmax can be used to detect additional stages of bearing failure using techniques

described in Preventative Maintenance literature.

ITEM BAND 1 BAND 2 BAND 3 BAND 4 BAND 5 BAND 6

BAND LOWER FREQ., CPM 1,904 6,426 11,424 35,700 64,260 92,820

BAND UPPER FREQ., CPM 6,426 11,424 35,700 64,260 92,820 178,500

BAND LOWER FREQ., HZ 32 107 190 595 1,071 1,547

BAND UPPER FREQ., HZ 107 190 595 1,071 1,547 2,975

BAND ALARM LEVEL 0.27 0.2 0.4 0.35 0.3 0.15