Section_11192_-_Sewage_Pumps.pdf

41055-081S11192 11192-1 Pump Station 22 Upgrade City of Homestead

SECTION 11192 - SEWAGE PUMPS

PART 1 – GENERAL

1.01 THE REQUIREMENT

A. The CONTRACTOR shall install all supplies, materials, equipment and labor necessary for the furnishing, installing, field testing, and placing into operation of the pumps and pumping appurtenances, complete and operable, all in accordance with the requirements of the Contract Documents.

1.02 RELATED WORK SPECIFIED ELSEWHERE

A. Equipment General Provisions

B. Pumps, General

C. Electrical General Provisions

D. Motors

E. Instrumentation

PART 2 – PRODUCTS

2.01 MANUFACTURERS

A. Sewage Pumps: Flygt, or Approved Equal

2.02 SEWAGE PUMPS

A. General

1. The pumps, electric motors and couplings shall be the standard product of a manufacturer which has produced and sold such pumps, couplings, and motors for a period of at least 5 years for similar service.

2. The pumping units shall be suitable for the design conditions stated herein and for the allotted space shown on the Plans.

3. The pump station shall have three (3) pumps that are totally submersible, electrically operated, capable of handling raw unscreened sewage. The design shall be such that the pump unit will be automatically and firmly connected to the discharge piping when lowered into place on its mating discharge connection which is permanently installed in the wet well. For this purpose there shall be no need for personnel to enter the wet well. The pump shall be so designed that it may be lowered to or raised from its place in the wet well by chain or cable and accurately guided by two pipe guide bars.

4. Each pump shall meet the operating requirements outlined below. The motor at the nameplate rating specified shall not overload anywhere along the entire characteristic

41055-081S11192 11192-2 Pump Station 22 Upgrade curve of the impeller. The pump design shall be such that the impeller is attached directly to the motor shaft.

5. Vibration shall not exceed 0.2 inches per second, velocity as measured by the Standards of the Hydraulic Institute. Pump structure shall have a first natural frequency at least twice the shaft maximum rotative speed.

6. Each pump with its appurtenances and cable shall be capable of continuous submersion under water without loss of water-tight integrity. Major parts such as stator casing, oil casing, sliding bracket, volute and impeller shall be of cast iron. All surfaces coming into contact with sewage shall be protected by a coating resistant to sewage.

All exposed bolts and nuts shall be Type 316 stainless steel.

7. The pump schedule shall be as follows, as required by these Specifications.

Operating Characteristics

a. Model FLYGT NP-3202 MT 3-643

b. No. of Units 3

c. Impeller Diameter (mm) 314

d. Station Operating Range, GPM at TDH, ft.

Point 1 (1 Pump) 2,585 gpm @ 30’ TDH Point 2 (1 Pump) 2,800 gpm @ 26’ TDH Point 3 (2 Pumps) 3,550 gpm @ 42’ TDH Point 4 (2 Pumps) 4,085 gpm @ 39.3’ TDH

e. Motor Speed, rpm 1,170

f. Motor Horsepower (1) (2) (non-overloading) 35

g. Connection Diameters; in.

Suction N/A Discharge 8”

h. Minimum solids passing; inch 3”

i. Fluid pumped Raw Sewage

(1) Along entire characteristic curve of impeller.

(2) Pump station wet well is classified as a Class 1 Division 1 hazardous location.

Submersible motor shall be explosion proof.

B. Pump Design

1. The pump shall be totally submersible, non-clogging, centrifugal, designed specifically for use in municipal wastewater applications, capable of handling raw unscreened sewage. There shall be no need for personnel to enter the wet-well. The pump shall automatically connect to the discharge elbow with a metal-to-metal watertight contact. The pump shall be guided by no less than two (2) separate stainless steel guide rails. Sealing of the discharge interface with a diaphragm, O-ring or profile gasket will not be acceptable. The pump shall not bear directly on the floor of the wet well.

C. Pump Construction

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1. The major pump components shall be ASTM A-48 Gray Iron Castings, Class 35B cast iron, with smooth surfaces devoid of blow holes and other irregularities; of sufficient strength, weight, and metal thickness to insure long life, accurate alignment and reliable operation. All exposed nuts and bolts shall be type 316 stainless steel. All surfaces coming into contact with sewage other than stainless steel or brass shall be protected by a factory applied spray coating of acrylic dispersion zinc phosphate primer with a polyester resin paint finish on the exterior of the pump. The pump exterior shall be sprayed first with PVC epoxy primer and then with chloric rubber paint finish. All remaining surfaces where watertight seal is required shall be machined and fitted with nitril rubber "O" rings. Fittings shall be such that the sealing is accomplished by metal-to-metal contact between the machined surfaces. Critical mating surfaces where watertight sealing is required shall be machined and fitted with Nitrile or Viton rubber O-rings. Fittings will be the result of controlled compression of rubber O-rings in two planes and O-ring contact of four sides without the requirement of a specific torque limit. Rectangular cross-sectioned gaskets requiring specific torque limits to achieve compression shall not be considered as adequate or equal.

No secondary sealing compounds, rectangular gaskets, elliptical "O" rings, grease or other devices shall be used.

2. The cable entry water seal shall be designed to preclude specific torque requirements to insure a watertight and submersible seal. The cable entry shall be comprised of a single cylindrical elastomer grommet flanked by washers, all having a close tolerance fit against the cable outside diameter and the entry inside diameter and compressed by the entry body containing a strain relief function separate from the function of sealing the cable. The assembly shall bear against the top shoulder of the pump.

3. The cable entry junction chamber and motor shall be separated by a stator lead sealing gland or terminal board, which shall isolate the motor interior from foreign material gaining access through the pump top. Epoxies, silicones, or other secondary sealing systems shall not be considered acceptable.

4. The pump motor cable shall be suited for submersible pump applications with Underwriters Laboratory approval permanently embossed on the cable. Cable sizing shall conform to the National Electric Code Specifications for pump motors.

5. The impeller shall be of grey cast iron, ASTM A-48, Class 35B, dynamically balanced semi-open, multi-vane, back swept, screw-shaped, non-clog design. The impeller leading edges shall be mechanically self-cleaned automatically upon each rotation as they pass across a spiral groove located on the volute suction. The screw-shaped leading edges of the impeller shall be hardened to Rc 45 and shall be capable of handling solids, fibrous material, heavy sludge, and other matter found in normal sewage applications. The impeller shall be of a single vane or closed non-clogging design. The screw shape of the impeller inlet shall provide an inducing effect for the handling of up to 5% sludge and rag-laden wastewater. The impeller shall be capable of passing a minimum 3" solid sphere. The volute shall be of single piece design and shall have smooth fluid passages, large enough at all points to pass any size solid which can pass through the impeller. The impeller to volute clearance shall be readily adjustable by the means of a single trim screw. The impellers shall be locked to the shaft, held by an impeller bolt and shall be coated with alkyd resin primer. A Wearing system shall be installed to provide efficient sealing between the volute and impeller.

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Each pump shall be equipped with a brass ring insert that is drive fitted to the volute inlet.

6. This pump shall also have a stainless-steel impeller wear ring heat-shrink fitted onto the suction inlet of the impeller.

D. Shaft

1. The pump shaft shall be AISI Type 431 Stainless Steel.

2. Each pump shall be provided with a positively driven dual, tandem mechanical shaft seal system consisting of two seal sets, each having an independent spring. The lower primary seal, located between the pump and seal chamber, shall contain one stationary and one positively driven rotating corrosion resistant tungsten-carbide ring.

The upper secondary seal, located between the seal chamber and the seal inspection chamber, shall contain one stationary and one positively driven rotating corrosion resistant tungsten-carbide seal ring all seal rings shall be individual solid sintered rings. Each seal interface shall be held in place by its own spring system. The seals shall not depend upon direction of rotation for sealing. Mounting of the lower seal on the impeller hub is not acceptable. Shaft seals without positively driven rotating members or conventional double mechanical seals containing either a common single or double spring acting between the upper and lower seal faces are not acceptable.

The seal springs shall be isolated from the pumped media to prevent materials from packing around them, limiting their performance.

3. Each pump shall be provided with a lubricant chamber for the shaft sealing system.

Seals shall run in an oil reservoir. The lubricant chamber shall be designed to prevent overfilling and shall provide capacity for lubricant expansion. The seal lubricant chamber shall have one drain and one inspection plug that are accessible from the exterior of the motor unit. The seal system shall not rely upon the pumped media for lubrication.

4. The area about the exterior of the lower mechanical seal in the cast iron housing shall have cast in an integral concentric spiral groove. This groove shall protect the seals by causing abrasive particulate entering the seal cavity to be forced out away from the seal due to centrifugal action.

5. A separate seal leakage chamber shall be provided so that any leakage that may occur past the upper, secondary mechanical seal will be captured prior to entry into the motor stator housing. Such seal leakage shall not contaminate the motor lower bearing. The leakage chamber shall be equipped with a float type switch that will signal if the chamber should reach 50% capacity.

6. The integral pump/motor shaft shall rotate on two bearings. The motor bearings shall be sealed and permanently grease lubricated with high temperature grease. The upper motor bearing shall be a single ball type bearing to handle radial loads. The lower bearing shall be a two row angular contact ball bearing to handle the thrust and radial forces. The minimum L10 bearing life shall be 50,000 hours at any usable portion of the pump curve.

41055-081S11192 11192-5 Pump Station 22 Upgrade

E. Pump Motor

1. The pump motor shall be NEMA B design, squirrel cage induction, shell type design, housed in an air filled, watertight chamber, 460 volts, 3 phase, 60 Hertz, 3530 RPM,

1.15 S.F. The stator winding and stator leads shall be insulated with moisture resistant Class H insulation rated for 180°C (356°F). The stator shall be insulated by the trickle impregnation method using Class H monomer-free polyester resin resulting in a winding fill factor of at least 95%. The motor shall be inverter duty rated in accordance with NEMA MG1, Part 31. The stator shall be heat-shrink fitted into the cast iron stator housing. The use of multiple step dip and bake-type stator insulation process is not acceptable. The use of pins, bolts, screws, or other fastening devices used to locate or hold the stator and that penetrate the stator housing are not acceptable. The motor shall be designed for continuous duty while handling pumped media of up to 104°F.

The motor shall be capable of withstanding at least 15 evenly spaced starts per hour.

The rotor bars and short circuit rings shall be made of aluminum.

2. Three thermal switches shall be embedded in the stator end coils, one per phase winding, to monitor the stator temperature. These thermal switches shall be used in conjunction with and supplemental to external motor overload protection and shall be connected to the motor control panel. Should the thermal switches open, the motor shall stop and activate an alarm. A float switch shall be installed in the seal leakage chamber and will activate if leakage into the chamber reaches 50% chamber capacity, signaling the need to schedule an inspection. The thermal switches and float switch shall be connected to a Mini CAS control and status monitoring unit. The Mini CAS unit shall be designed to be mounted in the pump control panel

3. Each unit shall be provided with an integral motor cooling system. A motor cooling jacket shall encircle the stator housing, providing for dissipation of motor heat regardless of the type of pump installation. An impeller, integral to the cooling system and driven by the pump shaft, shall provide the necessary circulation of the cooling liquid trough the jacket. The cooling liquid shall pass about the stator housing in the closed loop system in turbulent flow providing for superior heat transfer. The cooling system shall have one fill port and one drain port integral to the cooling jacket. The cooling system shall provide for continuous pump operation in liquid or ambient temperatures of up to 104°F (40°C). Operational restrictions at temperatures below 104°F are not acceptable. Fans, blowers, or auxiliary cooling systems that are mounted external to the pump motor are not acceptable.

PART 3 – EXECUTION

3.01 INSTALLATION

A. The CONTRACTOR shall install the pumps and appurtenances in accordance with the manufacturer's instructions and recommendations. The Vendor shall furnish the required oil and grease for initial operation. The grades of oil and grease shall be in accordance with the manufacturer's recommendations.

B. The CONTRACTOR shall install and adjust the pumps in such a manner that connecting piping will not impose any strain whatever on any pump. Pump shall be set upon level, fully grouted foundations so that connecting flanges, screwed connection, or flexible connections will meet without strain or distortion.

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3.02 PAINTING

A. Before exposure to weather and prior to shop painting, all surfaces shall be thoroughly cleaned, dry and free from all mill/scale, rust, grease, dirt, and other foreign matter.

B. Metal surfaces coming into contact with the pumpage, other than stainless steel or brass, shall be protected by a factory applied spray coating of acrylic dispersion zinc phosphate primer with a polyester resin paint finish on the exterior of the pump.

3.03 PUMP TESTS

A. The manufacturer shall perform the following inspections and tests on each pump before shipment from the factory:

1. Impeller, motor rating and electrical connections shall be checked for compliance with customer's purchase order.

2. Motor and cable insulation tests for moisture content or insulation defects shall be made.

3. Prior to submergence, the pump shall be run dry, to establish correct rotation and mechanical integrity.

4. Pump shall be run for 30 minutes submerged a minimum of 6 feet underwater.

5. After the operation tests, the insulation test is to be performed again. A written report, signed by a professional ENGINEER, registered in the state where the tests were performed, stating the foregoing steps have been satisfactorily accomplished, shall be supplied with each pump at the time of shipment.

3.04 SPARE PARTS

A. The CONTRACTOR shall obtain from the pump manufacturer a list of suggested spare parts of all items of each pump, motor, and drive, subject to wear, such as seals, packing, gaskets, nuts, bolts, washers, wear rings, etc., as well as a set of spare bearings. He shall furnish all these parts suitably packaged and labeled in a box as described above for tools.

3.05 WARRANTY

A. All pump factory warranties shall have an effective date of one year from the date of when equipment is placed into service for beneficial use. Copies of factory warranties for all pumps furnished shall be submitted in accordance with Section 01300, with the written guarantee, and shall be included in operation and maintenance manuals.

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