CHEMICAL FEEDING EQUIPMENT
PART 1 - GENERAL
1.1 WORK INCLUDED
A. The Contractor shall furnish and install chemical feeding equipment all shown on the Drawings and specified herein, with all accessories and appurtenances necessary to provide a complete and operable system. These Specifications direct attention to certain features of the chemical feeding equipment, but do not purport to cover all the details of their design. The equipment furnished shall be designed, constructed and installed in conformity with high quality standards.
B. New chemical feeding systems shall be provided for chlorine, powder activated carbon, and hydrofluosilic acid.
C. Conduit, wiring, and electrical interconnections are specified under the applicable electrical sections.
D. The Contractor shall make himself and his workmen and his subcontractors completely familiar with the hazards involved prior to their handling of any chemical or chemical solutions to be used on this project.
1.2 RELATED WORK
A. Division 13 - Special Construction. B. Division 15 - Mechanical.
C. Division 16 - Electrical.
1.3 SUBMITTALS
A. Descriptive literature, catalog cuts, dimension prints, shop drawings, and installation, operation and maintenance instructions shall be submitted to the Engineer for review before shipment.
The data shown on the shop drawings shall be complete with respect to dimensions, materials of construction, wiring diagrams, and the like, to enable the Engineer to review the information as required. At the time of submission, the Contractor shall, in writing, call the Engineer's attention to any deviations that the Drawings may have from the requirements of these Specifications.
B. Operating and Maintenance Instructions and Separate Parts Lists: Operating instructions shall also incorporate a functional description of the entire system including the system schematics which reflect "as built" instructions. Special maintenance requirements particular to the system shall be clearly defined along with special calibration and test procedures.
C. Special Tools: These shall be in a kit which shall contain special size wrenches, and other types of tools necessary for assembling, disassembling, aligning, and calibrating the equipment.
1.4 MANUFACTURER'S SERVICE
A. The equipment manufacturer shall supply and verify the installation of the equipment included in this Work.
PART 2 - PRODUCTS
2.1 CHEMICAL METERING PUMPS
A. Caustic Soda, Coagulant and Flouride Metering Pumps
1. Chemical metering pumps shall be of the positive displacement, mechanical diaphragm type. A steel and nodular iron non-loss-motion stroke adjustment mechanism, driven by a pulley coupled, variable speed DC motor, shall actuate a flat, teflon-faced composite diaphragm. Solenoid-driven pumps, lost-motion, mechanically actuated diaphragm pumps and hydraulically actuated diaphragm pumps will not be accepted. The liquid ends shall provide for easy maintenance via Kynar cartridge-type check valves. Each pump shall have a maximum capacity of 24.0 gph at a maximum back pressure of 175 psi. Each unit shall be as manufactured by Wallace & Tiernan, Milton Roy, Penn Processing or approved equal.
2. A steel and nodular iron non-loss-motion stroke adjust mechanism shall be housed in a corrosion resistant, epoxy painted, cast iron gearbox. All drive bearings shall be tapered rollers; all fasteners shall be 316 SS. The gearbox shall be oil-bath lubricated. Stroke length shall be controlled manually via a 10-turn micrometer-type adjuster. A percent scale and vernier shall indicated stroke length in 0.25% increments. Each revolution of the knob shall change stroke length by 10%.
3. The process diaphragm shall be teflon-faced, fabric reinforced and bonded to pre-formed elastomeric support. It shall incorporate convolutions, for unconstrained rolling action and a steel backing plate for volumetric accuracy. An o-ring groove in the head=s diaphragm cavity will provide for a complete leak-free seal. Positive flow shall be ensured via single ball cartridge-type check valves. The valve retainers shall be Kynar and shall compression seal to the pump head and pipe connectors via o-rings. Valve service or removal shall not require any disturbances to the pump head pipeworks. A secondary diaphragm shall completely seal and separate the pump head from the drive unit, to eliminate any risk of cross-contaminating gearbox lubricant and process fluid.
4. Feed rate shall be controlled manually, via a 10-turn micrometer-type stroke length adjuster.
Feed rate shall be infinitely adjustable from 0 through 100%. Stroke length shall be adjustable over a 10:1 operating range. Repeatable metering accuracy shall be "2% of full scale, at constant hydraulic conditions, over the operating range.
5. Stroke length shall be controlled automatically, via an actuator and compound loop controller. The actuator shall contain a reversible motor which shall position the stroke
length of the metering pump over a 10 turn rotary adjustment. Mechanical manual override
shall be provided with indication at the controller that the actuator motor has been disengaged. Actuator position in percent shall be indicated on the controller display. The actuator shall have a rating of NEMA 4X and shall be constructed of cast aluminum. It shall be accessible from the front for service.
6. The actuator shall contain three alarm relays with N.O. contacts rated at 5 amps at 250
VAC. The relays shall be dedicated for high limit, low limit (usable for no flow condition), and actuator motor disengaged.
7. The compound loop controller shall be microprocessor-based, and capable of accepting 3 input signals: flow, residual and one spare. It shall have a membrane touch keypad, digital LCD display of residual, LED bar graph display of percent speed and 16 character alphanumeric LCD display of all operating and set up parameters. The user shall be able to
select from six modes of operation: (1) direct residual control, (2) compound loop control,
(3) dual signal feedforward control for dechlorination, (4) center zero control for dechlorination, (5) flow proportional control, (6) manual control. Four configurable alarm relays shall be provided to select from 16 different alarm conditions. The controller shall have password protection to prevent tampering. A user configurable isolated 4-20 mA output signal shall be provided for control output, residual, actuator position and flow. The unit shall be capable of computer interface via RS485 serial communication.
8. The metering pumps shall be fitted with a diaphragm leak detection system for each pump head, to detect the early stages of diaphragm failure. The system shall consist of a solid state electro-optic sensor that mounts to the liquid end and a NEMA 4X control box. Each control box shall be capable of monitoring two liquid ends and shall provide both local and remote indication of failure via LED=s and a relay.
9. Each pump shall be provided with a calibration standpipe for calibrating pump output. The standpipes shall be Schedule 80 clear PVC pipe with Schedule 80 fittings. Thin wall tubing
and acrylic plastics shall not be used. Each standpipe shall be equipped with a flanged connection to its manifold, and an end cap fitted with all PVC vacuum breaker and a ball valve for air venting. All fittings shall be socket weld type. All valves and fittings shall be as specified under Section 15065, Chemical Piping, Valves and Appurtenances. The standpipes shall be capable to function as suction line pulsation dampeners. Their size and shape shall be determined such as to satisfy this function (as well as the calibration function). The standpipe dimensions and graduations shall be such as to allow convenient observation and measurement of the respective pump draw-down volume at maximum discharge rate setting between (and including) 0 and 100 percent, for a time span of approximately 30 seconds. The graduation accuracy and density shall be such as to allow a convenient determination of the fluid contents of the standpipe with an accuracy of plus or minus one-half of one percent of span.
10. Valves and flanges shall be provided at each pump suction for attachment of the calibration standpipes. Pump suction and discharge piping shall be installed so as not to interfere with the location and use of the standpipes.
11. All accessories necessary to provide a complete, operable and safe chemical feed system shall be provided. These accessories shall include but not necessarily be limited to pump suction strainers, pressure relief valves, and pulsation dampeners.
2.2 CHLORINE FEED EQUIPMENT
A. General Description:
1. An automatic switchover system shall be furnished to change over to a new supply as the on-line supply is depleted. Two vacuum regulating valves shall be furnished. Each shall have internal pressure relief. The regulating valves shall include a mechanical detent to keep the standby gas supply ready for on-line service. When switchover is accomplished, gas shall continue to be drawn from the former source until the container(s) are empty. The automatic switchover capability shall be built into the vacuum regulators. A separate switchover device is acceptable.
2.3 CHEMICAL TRANSFER PUMPS
A. Transfer pumps for caustic and ferric floc shall by 45 gallons per minute as manufactured by
March Pump, Model TE-7K-MD, 3/4 HP.
B. Transfer pumps for fluoride shall be Teel High Flow Drum Pump No. 2P363 with No. 2P094 suction tube.
PART 3 - EXECUTION
3.1 INSTALLATION
A. Installation shall be in accordance with the manufacturer's recommendations.
3.2 TECHNICAL ASSISTANCE
A. The Contractor shall furnish the services of an experienced and qualified manufacturer's technician to supervise the installation, start-up and calibration of the equipment specified in this Section.
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