SECTION 11221 RAPID (FLASH) MIXER

SECTION 11221
RAPID (FLASH) MIXER

PART 1 - GENERAL

1.01             SCOPE

A.       The mixer assembly shall be supplied complete with electric motor, gear reducer, shaft and impeller assembly.   Entire assembly shall be mounted on common baseplate or pedestal.   Tank, mixer supports, and other appurtenances necessary for proper operation shall be provided by others in accordance with the manufacturer's recommendations..

B.       The mixer shall be the product of a recognized manufacturer that has been regularly engaged in the design and manufacturing of mixers for at least ten years.

C.       The manufacturer shall be responsible for the detailed design of the equipment to be furnished, the preparation of the required submittal data including operation and maintenance manuals, and technical supervision for installation of the equipment.

D.       The mixers shall be SHARPE N-Series type as manufactured by SHARPE MIXERS, or approved equivalent.


PART 2 - PRODUCTS

2.01             Only drive units specifically designed for agitator service and suitable for 24 hour per day operation under moderate to heavy shock loads will be acceptable.   Each drive unit shall consist of an electric motor and a gear reducer with a flexible coupling provided between the motor and gear reducer.   Direct-connected motors, hollow-shaft connections and integral gearmotors are not acceptable.

2.02             Each mixer drive shall consist of a rugged grey cast iron speed reducer.   Housing shall be SAE Class 30.
Lifting lugs shall be provided on the speed reducer and motors, above 180TC frame.   Motor shall be readily separable from gear reducer.

2.03             The gear reducer shall be parallel-shaft, double or triple reduction utilizing only helical gearing.   All helical gears shall be fabricated from SAE 8620 steel, carburized to a hardness of 58-62 Rockwell C. Gears shall be ground to AGMA Quality Level 12.   Gear drive shafts shall be oversized to accommodate all overhung loads.

2.04             High speed input shaft bearings shall be heavy duty ball bearings.   Intermediate shaft bearings and low speed output shaft bearings shall be tapered roller bearings.   All bearings shall have a minimum B-10 rating of 100,000 hours.

2.05             Gear reducer lubrication shall be by means of an oil bath.   All bearings shall be oil lubricated.   Low speed output shaft shall be sealed using double quadralip oil seals.   Oil drain and fill plugs shall be easily accessible.   Gear reducer shall carry a minimum AGMA service factor of 2.00 based on motor nameplate horsepower.   Rating is based on electric motor driven speed reducers operating 24 hours per day under moderate to heavy shock load conditions.   All drive components shall be designed for outdoor or other environmental conditions, as noted.

2.06             Mixer shaft shall be designed to withstand all torsional and bending stresses without the use of bottom or intermediate shaft bearings.   Combined shaft stress shall not exceed 8,000 psi based on a material ultimate yield stress of 30,000 psi.   Operating speed shall not exceed 70% of first natural lateral critical speed.   Shaft shall be straightened to a maximum total indicated runout of 0.003" per foot of length.

2.07             Impellers shall be four blade design attached to a central hub.   Impeller attachment to shaft shall be by means of a key and keyway or by means of a split and clamped hub arrangement.   Method of attachment shall be adequate to transmit 150% of operating torque.

2.08             Electric motors shall be NEMA B design, squirrel cage induction type for normal starting torque.
Motors shall be vertical, shaft-down, C-flange mounted with TEFC enclosure, 1.15 service factor, and class F insulation, suitable for operation on 3/60/230-460V service.   Motor shall be connected to gear reducer through a flexible coupling.   Coupling shall be rated for 150% of operating load.   Motors shall be inverter type where variable frequency drives will be used.


PART 3 - EXECUTION

3.01             The Contractor shall install mixing   equipment in strict accordance with the manufacturer's installation drawings, instructions and  recommendations.   The  Contractor shall obtain the  services of  a  field supervisor employed by the   manufacturer for inspection of completed installation and startup of equipment.

3.02             Installation and assembly shall be performed in strict accordance with the manufacturer's drawings and written instructions.

3.03             Supervisory services of a factory trained field service engineer shall be provided for a period of two days on-site  for  inspection of  completed installation and  startup  of  equipment.    The  services of  such designated manufacturer representative shall be included in the contract price.   The service times specified above shall be considered as full eight (8) hour working days and does not include travel time.

3.04             ACCEPTANCE TESTS

A.      After installation of the equipment, and after completion of the services of the manufacturer's representative the Contractor shall operate each unit to demonstrate its ability to operate continuously without vibration, jamming, or overheating and to perform its specified functions satisfactorily.

B.       All defects and defective equipment shall be corrected promptly or replaced at the expense of the
Contractor.

C.       All final adjustments necessary to place the equipment in satisfactory working order shall be made at the time of the above tests.