Automatic Tube Brushing System


Automatic Tube Brushing (ATB) System
General Specification

1.0 General:

An Automatic Tube Brushing (ATB) System shall be installed on each chiller (heat exchanger) condenser (and absorber in absorption units) to provide optimum tube cleanliness and heat transfer. The systems are to be manufactured and installed by Water Technology of Pensacola, Inc., Pensacola, Florida.

2.0 Product Description:

The ATB System automatically maintains tube fouling at or below design conditions without interrupting normal equipment operation.

The ATB System consists of a special nylon brush inserted in each tube and a low-pressure drop catch basket attached to each end of the tube. A custom-made four-way reversing valve is installed to permit reversing the direction of water flow. The reversed water flow pushes the brush through the tube, removing tube deposits. The brush is caught in the opposite end basket and remains there until flow is reversed again in 30 seconds, thus repeating the process.

The frequency of the reversing cycle is set up to match job conditions (normally every six hours). The four-way reversing valve pneumatic (or electric) actuator is controlled by a pre-set time cycle that assures regular tube brushing during equipment operation.

3.0 Equipment Specification:

3.1 Turbo Brush and Basket Sets: One (1) set per each condenser tube.

3.1.1 Turbo Brush (One (1) per set): Each brush to be nylon bristle, titanium wire and polypropylene tipped. One tip to have vanes to cause increased spiraling of brush through tubes for superior cleaning. Brush to have interference fit with ID of tube not to exceed 0.025" interference.

3.1.2 Basket (Two (2) per set): Low pressure-drop design, polypropylene basket with removable 4-prong end-clip; neck outside diameter to press fit inner diameter of tube. End-clip shall not restrict basket end more than 25%. Basket shall allow for removal and replacement of brushes from tubes.

Epoxy for Basket Installation: Special two-part water-proof epoxy for basket installation to have similar co-efficient of expansion as tube material.

Tool: Special tool for installation of baskets.

3.4 Four-Way Valve: Valve shall be Water Technology's Standard HX Valve and shall be of steel construction (A 36 or better), positive sealing type, with all internal sealing parts of hard rubber and 304 Stainless Steel. Valve shall have parallel flow connections to minimize field installation piping and labor. It shall be manufactured in accordance with ASME Unfired Pressure Vessel Code Specification per Section VIII for operation at a system working pressure of 125 PSIG with a maximum system differential of 35 PSIG. End connections shall be flanged, victaulic or plain, as required. Valve shall be hydro-statically tested to 1.5 times designed working pressure. Valve shall allow for manual fail-safe turning, and have a mechanical position indicator.

3.5 Pneumatic Actuator: To be pre-mounted on the valve. Double actuating cylinder to assure trouble-free operation. Operation to be on 50 (minimum) to 100 (maximum) PSIG air pressure supplied by others.

3.6 Position Control Switches: Micro-switch to be supplied to indicate complete turn of four-way valve in normal and reverse flow.

3.7 Control Panel: The on-load control shall have the following features:

Nema 4x enclosure with mounting bracket.
Cycle counter.
24-hour timer to automatically initiate the on-load cleaning cycle.
Manual Override of pre-set cleaning cycle.
Power On light.
Diverter Position Indicator lights:
- Normal Flow
- Reverse Flow
Malfunction Light - To indicate slow turning or incomplete valve turning.
Solenoid valve for actuator operation, to be mounted at control panel or actuator.
Flow Switch Bypass.
Electric Chiller Unloading.

3.8 Operation and Installation Manual: Two (2) copies to be provided.

4.0 Shop Testing: In addition to tests specified for the valve, Manufacturer will functionally test the entire system prior to shipment, including valve, actuator, solenoid valve, position indicator and control panel.

5.0 Field Supervision: Manufacturer shall supply field supervision of brush and basket installation to assure proper installation and to protect manufacturer's warranty.

6.0 Field Service and Replacement Parts: Manufacturer will maintain at all times an adequate inventory of replacement parts that are available for immediate shipment. Qualified field service personnel shall be available from manufacturer (at added cost) on short notice to service or repair equipment furnished.

7.0 Warranty: Manufacturer shall guarantee system, when operated according to its instructions, and shall provide a fouling factor in the condenser of .00025 or better.

Manufacturer to warranty components for one year against defective materials and workmanship. Defective parts to be returned freight prepaid to factory and will be replaced FOB from manufacturer's plant.

Installation labor to be warranted 45 days from beneficial use.

8.0 Order Procedures:

8.1 Manufacturer: The ATB System is manufactured exclusively by:

Water Technology of Pensacola, Inc.
3000 West Nine Mile Road
Pensacola, Florida 32534
TEL: 850-477-4789
FAX: 850-479-3056

8.2 Information (to be supplied by customer if possible):

8.2.1 Chiller tonnage, Model No., manufacturer.
8.2.2 Pipe connection size.
8.2.3 Condenser flow rate.
8.2.4 Tube size: End ID and ID at finned area.
8.2.5 Number of tubes.
8.2.6 Condenser head clearance from inside of head to Tubes sheet (2 1/4" required).
8.2.7 Piping sketch or drawing.

8.3 Delivery: 10 - 12 weeks after receipt of order.

8.4 Schedule: Factory to be notified 3 weeks in advance of required installation date.