HVAC Water Treatment ME- Building Group
SECTION 232500 – HVAC WATER TREATMENT
PART 1 - general
1.1 RELATED DOCUMENTS
- Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division01 Specification Sections, apply to this Section.
1.2 SUMMARY
A. This Section includes the provision of all the materials, equipment and chemicals to provide complete chemical treatment systems for the pertinent mechanical systems.
1.3 SYSTEM DESCRIPTION
A. Provide complete chemical water treatment systems.
B. Provide chemicals required for the water treatment systems in sufficient quantities for cleaning, flushing, refill and initial startup and operation of the systems until accepted by the Owner.
C. Provide controls, control wiring, motors and starters. Refer to Division 26 Sections “Common Work Results for Electrical” and Division 23 Sections “Common Motor Requirements for HVAC Equipment” for electrical requirements for motors and starters and electrical items.
D. Provide all chemical feed tubing inside PVC support piping.
1.4 SUBMITTALS
A. Manufacturer's Instructions: Submit instruction in the safety precautions, usage, storage and procurement of chemicals.
1.5 QUALITY ASSURANCE
A. Electrical Components, Devices, and Accessories: Listed and labeled as defined in NFPA70, Article100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended use.
PART 2 - PRODUCTS
2.1 COOLING TOWER CHEMICAL TREATMENT SYSTEM
A. Manufacturers
1. Betz/Dearborn.
2. Owner approved substitute.
B. System Description
1. Provide a system that automatically controls corrosion, scale, and microbiological growths in the open recirculating cooling water system. Provide all necessary cleaning and maintenance chemicals, control and feeding equipment, service and monitoring.
2. Provide a system that includes an integrated microprocessor based control and data acquisition system capable of monitoring and/or controlling conductivity, relative alkalinity, multifeed biocides, inhibitors, temperature, real time, and chemical drum low level; chemical feed pumps; bleedoff control valve; water meter; testing equipment; accessories; factory prefabrication; chemical treatments and services as specified.
C. Treatment Chemicals: Pipe treatment chemicals to appropriate points in the system by positive displacement pumps. Pump chemicals directly from the shipping containers or from suitable bulk storage containers if available. Control and meter the recommended chemical levels by the following automatic chemical feed system.
D. Control Equipment
1. Provide one integrated, key pad programmable, microprocessor based control system in a primed and painted NEMA 12 enclosure with a continuously hinged door, dual padlocking hasps, duplex receptacles and an 8-foot 3-wire cord with molded plug. Provide the door with a Lexan viewing window so that all readouts will be continuously visible while the door is closed, maintaining NEMA 12 integrity.
2. Provide for system measurements, programming data, setpoint calibration adjustments and real time clock adjustments to be accessed through the 16-key chemically resistant membrane key pad and all readouts to be indicated on a seven-segment, six-digit, 1/2-inch LED code and data display.
3. Indicate each operating switch and each operating function by a long-life red LED. Provide for the controller to provide temperature corrected measurements by reading water temperature and adjusting pH and conductivity valves according to a known temperature curve. Operating range: 0-100 degrees C with an adjustable high temperature alarm.
4. Provide for the conductivity controller to accurately monitor and maintain the desired level of Total Dissolved Solids (TDS) in the system by actuating the bleedoff solenoid valve when the dissolved solids level exceeds the trip point. Provide for readout of the system conductivity to be switch selectable from either of the two field selectable scales to assure accurate measurements. Provide measurement that is linear throughout the full span of conductivity ranges available, from 0-10,000 micromho/cm and the conductivity differential field adjustable.
5. Provide an adjustable bleed limit timer, programmable in one minute increments to 23 hours 59 minutes, to prevent excessive bleedoff by initiating an alarm when the timer has timed out. Provide factory set alarms for high and low conductivity at 20 percent above and below the trip point and capable of operator adjustment. Provide a quick disconnect type dense graphite conductivity probe and a quick disconnect type temperature sensor both furnished mounted in the flow assembly.
6. Provide a pH monitor that accurately monitors the relative alkalinity (pH) of the system. Provide readout of the system pH values that is linear over the full range of 0-14 pH units. Provide an adjustable feed limit timer, to be programmable to independently feed acid in one minute increments to 23 hours 59 minutes. Provide alarms for high and low pH that are operator adjustable. Provide a quick disconnect type sealed combination silver/silver chloride reference pH electrode mounted in the flow assembly.
7. Provide a biocide feed controller that is a programmable, two channel, 24-hour, 28-day timer that controls two biocide metering pumps. Provide for each channel of the timer to be programmable to independently feed one of the two biocides on an hourly, daily or weekly basis. Employ a secondary bleedoff timer to lower conductivity in the system prior to biocide feed to provide increased bleed off so that the system conductivity will not rise above the standard operation trip point when bleed lockout is activated.
8. Provide an interval timer network in the controller to allow for the programmed feeding of inhibitors and dispersants based on any one of the following field programmable modes:
a. A counter-timer network which accepts a low voltage impulse from an electrical contact head on the make-up water meter and activates two chemical feed pumps to independently feed inhibitors and dispersants in proportion to the amount of makeup added to the system.
b. A percentage timer which activates chemical feed pumps based on an adjustable time-proportioning basis initiated by bleedoff.
c. A clock timer which activates chemical feed based on a 24-hour timer with 1, 7, 14 or 28-day repeating cycle. Each chemical feed interval may be programmed for start time and duration with up to 15 intervals per function.
9. Protect the control system from power outage by a nickel/cadmium rechargeable battery backup system which maintains the program during power outage.
10. Provide the following equipment, accessories and options, mounted, piped and wired as part of the factory prefabricated package:
a. One flow switch and back check valve assembly to monitor the flow of recirculating cooling water and provide the flow proving signal to the controller. Loss of flow in the recirculating system will disable the output functions of the controller, but will not disrupt power to the clock and program functions of the controller.
b. Low drum level alarms for each pump output to prevent loss of pump prime by shutting off the pump and initiating a low level alarm condition.
c. All alarms indicated both visually and audibly. Include with the audible alarm a silencing feature that will allow manual silencing of the buzzer, but leave the visual alarm indication lit until the alarm condition is corrected.
d. A dual channel analog and a four-channel event recorder to simultaneously and continuously record the conductivity and pH values and four events on thirty-day strip charts. Record the following events: Bleed, Inhibitor Feed, Dispersant Feed, and Biocide Feed.
e. One serial line with documentation and RS 232C port for Building Management System connection.
f. Provide a general alarm to the chilled water system control panel.
E. Inhibitor Chemical Pump: Provide an inhibitor chemical metering pump of the single diaphragm, positive displacement type with Simplex PVC head and Viton or Teflon diaphragm and valve seats. Totally enclose the drive train so as to have no exposed moving parts. Provide the pumping capacity to be manually adjustable over the entire output range while the pump is running. Electrical requirements: 115/1/60. Pressure rating: not less than 200 percent of the dynamic head of the system at the point of chemical injection or 75 psi, whichever is greater. Pumping capacity: as shown in paragraph "Equipment Schedule".
F. Dispersant Chemical Pump: Provide a dispersant chemical metering pump of the single diaphragm, positive displacement type with head of PVC, Plexiglass or Lucite acrylic, and diaphragm and valve seats of Hypalon or Teflon. Totally enclose the drive train so as to have no exposed moving parts. Provide the pumping capacity to be manually adjustable over the entire output range while the pump is running. Electrical requirements: 115/1/60. Pressure rating: not less than 200 percent of the dynamic head of the system at the point of chemical injection or 75psi, whichever is greater. Pumping capacity: as shown in paragraph "Equipment Schedule".
G. Biocide Chemical Metering Pumps: Provide two biocide chemical metering pumps of the single diaphragm, positive displacement type with head of pvc, Plexiglass, or Lucite acrylic, and diaphragm and valve seats of Hypalon or Teflon. Totally enclose the drive train so as to have no exposed moving parts. Provide the pumping capacity to be manually adjustable over the entire output range while the pump is running. Electrical requirements: 115/1/60. Pressure rating: not less than 200 percent of the dynamic head of the system at the point of chemical injection or 75psi, whichever is greater. Pumping capacity of each pump: as shown in paragraph "Equipment Schedule".
H. Pump Safety Package: Equip each pump with an injection check/anti-siphon valve; suction and discharge tubing; and a pump safety package consisting of an extended foot valve assembly and a four-function valve providing anti-siphon, back pressure, line pressure release, and pressure relief functions.
I. Accessories
1. Provide the following equipment, accessories and options for installation in the piping system:
a. One water meter with totalizing register reading in U.S. gallons equipped with a momentary contact electrical switch set to close at a preset volume to initiate the chemical feed cycle. Install the meter in the cooling tower makeup water line, with a 3-valve by-pass for servicing, with electrical connection to the control panel. Meter size: as shown in paragraph "Equipment Schedule".
b. Provide the water meter with a fixed rate flow controller to protect the meter from flows in excess of its capacity. Install the flow controller on the makeup line immediately upstream of the meter. Provide the flow capacity of the flow controller to be equal to the peak flow capacity of the water meter.
c. One electric solenoid bleed valve with manually adjustable flow control valve for installation at a suitable location in the bleedoff line. Rate the bleedoff valve for 125psi maximum differential pressure. Valve size: as shown in paragraph "Equipment Schedule".
d. One sample stream corporation stop and injection assembly for installation in the circulating line.
J. Testing Equipment
1. Provide a test cabinet for onsite testing of all applicable chemical control parameters that includes a painted steel, wall mounted, lockable cabinet with slide out tray, interior fluorescent light, and three wire grounded plug. Furnish cabinet with instructions, glasswire, and an initial supply of all reagents required to perform tests necessary to maintain proper treatment residuals.
2. Provide a 1/2-inch cooling water sample line with sample cock located convenient to the test cabinet constructed of the same material as the rest of the piping or of schedule 80 PVC.
3. Provide one bypass corrosion coupon test loop with not less than 4 corrosion coupon mounting plugs to facilitate the regular monitoring of system corrosion rates. Pipe test loop across the circulating pumps or otherwise so as to insure a flow of at least 0.315 L/s (5 gpm) past the test coupons.
4. Provide one test work station.
K. Equipment Schedule
Bleedoff valve size: 1 inch
Makeup water meter size: 3 inches
Inhibitor pump capacity: 0.69 gph
Dispersant pump capacity: 2.0 gph
Biocide pump capacity: 3.0 gph each
2.2 BY-PASS SHOT FEEDERS
A. Provide for the Closed Loop Chilled Water system, a by-pass shot feeder to add chemical treatment to the water systems.
B. Provide each feeder with air vent and drain petcocks, funnel and funnel valve and Pyrex gage glass fittings. Equip the feeders with two blind tapped machine thread mounting holes in the back of the tank for wall mounting.
C. Fabricate tank of cast iron, with a 1.7 gallons capacity with 1/2 inch piping connections, 7 inches diameter by 26inches in overall height.
D. Burmah Model BF-200 or as approved by the Owner.
PART 3 - EXECUTION
3.1 PREPARATION
A. Chemical Treatment Program - Chilled/Hydronic Systems
1. Flushing
a. Refer to Division 23 Section “Cleaning and Flushing of HVAC Piping Systems.”
2. Cleaning
a. Immediately after the hydrostatic testing has been completed, drain the entire closed system. Flush with clean water, and refill with clean water to which the appropriate cleaning compound has been added.
b. Then circulate the system for at least 48 hours, then drain and flush with clean water to remove pipe dope, fabrication lubricants, oils, welding slag, loose mill scale, and other extraneous materials. Immediately fill the system with clean water to which the appropriate corrosion inhibitor has been added.
B. Disposal: Provide for the legal disposal of cleaning compounds and water used to flush the systems.
3.2 PREFABRICATED PIPING AND WIRING
A. Factory prefabricate the control panel, chemical metering pumps, chemical injection, conductivity probe flow assembly, pH probe flow assembly, pH probe flow assembly, and flow switch on a steel mounting frame for ease of installation.
B. Provide all sample line bypass piping on the frame 1-inch-diameter schedule 80 CPVC and include two shut off valves, one back check valve, and one sample petcock. Mount and pre-wire above components. Field install and wire the water meter, bleedoff valve, and sample bypass supply and return piping from the frame. Pipe the sample bypass line across the circulating pumps or otherwise so as to insure a flow rate of at least 5 gpm.
C. Provide sample bypass return piping from the frame to the system minimum 1-inch-diameter schedule 80 CPVC and include a 1-inch schedule 80 PVC injection nozzle with injection quill and union type shutoff ball valve, and a 1-inch CPVC shutoff valve for field installation at point of bypass line reinjection.
3.3 SERVICE
A. Provide a service program, including technical assistance to the Contractor during installation, instruction in chemical cleaning, instruction of Owner's personnel in the operation, monitoring, and control of the chemical treatment system, and start up of the chemical treatment system. Maintain a continuing program of service and supervision, including service calls as required during flushing, cleaning, startup and commissioning and acceptance of the system.
END OF SECTION
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Revision Date: 01/21/14 Project & Bid Package
File name: 232500 HVAC WATER TREATMENT