Box Cell Retrofit Specification Guide

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This Specification Guide is meant to provide a roadmap of the typical decision path that customers face when retrofitting their ED paint tank with TECTRON ME Cells


Approved Materials:

Use only materials specifically approved by the vendor of the ED paint.

Demolition and Preparation:

Remove original box cells. Replace original box cells with an appropriate number of TECTRON XL/HD ME Cells. Use mini Supply & Return Manifolds to connect anolyte circulation system to TECTRON Cells. Provide means to support TECTRON Cells.

Membrane Electrode Cells:

At minimum the project should replace the total wetted electrode surface area of all the original box cells. Alternatively, the number of Cells required will increase or decrease based on acceptable anode current density limits or other such criteria as so defined.

Electrolyte Holding Tank:

Generally large enough and no new work is required.

Circulation Pump:

Vertical CPVC pump with a rating designed to supply electrolyte solution to every ME Cell.


Update conductivity controller to (0-1000 milliSiemens/cm) gauge so it will add DI water to dilute electrolyte when necessary.


Increase PVC Supply & Return Manifold size if anolyte pump needs to be increased.

Mechanical Support:

Add Cell support as required.

Electrical Connections:

Use a star network to branch out to new TECTRON Cells from existing power supply points.

DI Water:

Confirm there is a carbon filter.

ME System Design Specification

First Class Quality & Approved Materials

All material and workmanship shall be first class. The following materials are generally approved for use with ED paint: PVC; 304 stainless steel (except for Electrodes, which are to be 316L stainless steel, or better); polypropylene; polyethylene; hypalon; viton; Teflon; neoprene; and EPDM. If there is any question, then the ED paint supplier should be consulted first.

Demolition and Preparation

One the original box cells are removed, the tank can be prepared to accept the TECTRON Cell. UFS Corporation manufactures a Cell support frame designed for box Cell retrofits. The frame size is determined by the width of the old cell and the gap between cells. The Cell support frame is secured to the rim of the tank. Mini supply and mini return manifolds attach to the existing supply and return manifolds and are designed to divert flow to the appropriate number of TECTRON Cells. TECTRON Cells can be installed directly on the Cell support frame with the 2 pc metal clamps. ME Cells

Electrode Area, Base Bid

The amount of Electrode area shall be calculated by estimating the wetted surface area of the box cell. This is done by taking the submerged height and subtracting 50 mm (2 in) for the bottom flange. The wetted width dimension is the width of the box cell less 75 mm (3 in) for the side flange areas. Then multiply these two numbers together.

Electrode Area, Alternate(s) Bid

If the desired film thickness is less than 22 microns (0.9 mil) or more than 28 microns (1.1 mil), then an alternate method may be employed. First, the paint deposition factor (amp-minute/m2-micron, or amp-minute/SF-mil) must be known. TECTRON SD™ Cells have been operated for many years now up to levels of 50 amps/m2 (approximately 5 amps/SF) and the objective of this method is to estimate the actual current to be expected when the e-coat system performs work. The calculation is as follows:

Estimated Current	= painted through-put rate x deposition factor x film thickness
= m2/minute x amp-minute/m2-m x m
= amps

For high speed, high painted through-put systems, typical Electrode current densities are set at about 35 amps/m2 (approximately 3.5 amps/SF) and slower, lower painted through-put systems approach the higher Electrode current density.

Electrode Area	= estimated current ¸ 35 amps/m2
= m2

Some automotive firms have revised their specifications and now require the use of 2.5 minutes (not 2 minutes) when employing the 4:1 Rule. Membrane Electrode Cells The Membrane Electrode Cells shall be TECTRON Cells manufactured by UFS Corporation.

The only metallic portion shall be the Electrode. All other components shall be made from entirely non-metallic, light-weight, non-conductive materials. The ion-exchange membrane shall be selected based upon the type of ED paint and the expected duty cycle.

The Electrode shall be selected in a similar manner Replace original box cells with an appropriate number of TECTRON XL/HD ME Cells. Use mini Supply & Return Manifolds to connect anolyte circulation system to TECTRON Cells. Provide means to support TECTRON Cells.

The effective length of the side Cell shall be at least as tall as the height of the work package envelope. If possible, the effective length of the Cell should be equal to the height of the work package + submergence (distance from liquid level to top of work package envelope) + 50 mm (2”). The Cell can be made in any length up to 2.9 m (114.2 in) as an individual unit, with the standard lengths shown below.

  TectronTM T1 Anode Cells TectronTM T2 Anode Cells TectronTM T3 Anode Cells TectronTM T5 Anode Cells
Electrode diameter mm (in) 48.26 (1.900) 60.33 (2.375) 88.90 (3.00) 141.30 (5.563)
Effective length mm (in) Surface area sq meters (SF) Surface area sq meters (SF) Surface area sq meters (SF) Surface area sq meters (SF)
910 (35.8) 0.138 (1.49) 0.172 (1.86) 0.254 (2.74) 0.404 (4.35)
1400 (55.1) 0.212 (2.28) 0.265 (2.86) 0.391 (4.21) 0.621 (6.69)
1900 (75.8) 0.288 (3.10) 0.360 (3.88) 0.531 (5.71) 0.843 (9.08)
2300 (90.6) 0.349 (3.75) 0.436 (4.69) 0.642 (6.91)  
2900 (114.2) 0.440 (4.73) 0.550 (5.92) 0.810 (8.72) 1.287 (13.86)
Multiplier 0.15 sm/m or 0.49 SF/ft 0.189 sm/m or 0.62 SF/ft    
Center to Center Spacing Minimum MM (IN) 150 (6) 190 (7.5) 300 (12) 450 (17.75)

Cells can also be ganged together to span up to about 6 m (236.3 in). In a conventional Membrane Electrode System the Cells are placed along the side walls of the ED tank. The number of Cells can then be easily established:

Number of Cells	= Electrode area ¸ area/Cell + 2 Cells
= m2 ¸ m2/Cell + 2 Cells (round up to an even number)

Newer ED systems as well as higher through-put systems are employing Electrode cells not only on the side walls of the ED tank, but also on the floor and above the roof of the auto body. This is being done for several reasons: reduce paint consumption, improve film build on roof and interior, and lower energy consumption. Cell Layout Spacing - Monorail The first Cell is placed at the same point as the leading edge of the first box cell. The last Cell is generally at the same point as the trailing edge of the last box cell. The first 3 to 5 Entrance Cells should be at the minimum spacing. The spacing of the last two Cells should be at the minimum and exit can be at the 2 times the minimum. The balance of the Cells in the middle should be spaced accordingly.

Cell Layout Spacing - Hoist

Cells are generally placed along the two long sides of the ED tank. For ED tanks with an aspect ratio closer to 1 (i.e. square tank as seen in the plan view), Cells can be placed on all four walls. Add to this section. In either situation, the Cells generally begin near the placement of the edge of the ware and extend to the other edge of the ware. Cells should not be placed closer together than the minimum spacing.

Holding Tank

This is generally large enough for the TECTRON Cells. Only in unusual circumstances where the required ED film thickness has been greatly increased, will the tank need to be changed. Confirm that the tank (i.e. and the anolyte solution) is properly grounded.

Circulation Pump

Depending upon the age of the ED system, the anolyte pump may have to be upgraded. Many years ago the practice was to size the anolyte pump on a basis of 1-1/2 gpm per box cell. The present design basis is to use 8 lpm per square meter of electrode area (2 gpm for every 10 SF). The pump shall be a seal-less type vertical CPVC style and thus avoid seal damage by errant paint solids. The pump flow rate shall be calculated by using 8 lpm/sm (2 gpm/10 SF Electrode area) and then adding 20% as a safety factor. The pump head capacity shall be at least 1.5-2 bar (22-28 psi) more if the pump is located more than 3 meters (10 feet) below the rim of the ED tank. There shall be a pump by-pass loop back to the holding tank with a throttling valve. The electric motor shall be 3 phase, 460 volt, TEFC style. The required flow rate for any horizontal Cell needs to be about twice, or 16lpm/sm (4 gpm/10SF), in order to completely purge oxygen for the Cell.

Generally, a new pump/motor will require a new starter/disconnect switch, as well as larger line wire to the motor.


The electrolyte circulation system shall be fitted with the following controls: 0-20,000 (or 0 to 1000 milli Siemens/cm) microSiemens/cm analog conductivity controller, plastic/stainless steel conductivity sensor, 0-2 bar (0-30 psi) guarded pressure gauge, roto-meter flow meter, check valve, main control valve (NO), 110 volt DI water solenoid valve, low tank level switch, and tank drain valve. The conductivity controller should be located near eye level about 1.5 m (5’) away from the holding tank. If the original cell circulation system was modified or does not have these features then add them as required.

Electrolyte Manifold Piping

If the pump needs to be increased, then so do the Supply and Return Manifolds for the electrolyte solution that flows though the ME Cells. If the pump is large enough, then you may jump to the last paragraph of this section. All piping shall be PVC. Supply Manifold branch piping (i.e. on each side of the ED tank) shall be at least a PVC 50 mm (2”) Schedule 80 minimum and sized so that the average flow rate is no more than 0.25 – 0.5 meters/sec (3 –5 ft/sec). The size of the Supply Manifold main trunk piping to the Tee (i.e. where the branch piping begins) should be at least one size larger than the branch piping.

The Return Manifold branch piping shall be at least 75 mm (3”) PVC Schedule 40 minimum with PVC DWV type fittings. It shall be sloped downwards (i.e. towards the electrolyte holding tank) at a 21 mm per meter (¼ in per foot) slope and sized so the branch piping is never more than ¾ full. The size of the Return Manifold main branch piping to the Tee (i.e. where the branch piping begins) should be at least one size larger than the trunk piping. A 0-2 bar (0-30 psi) guarded pressure gauge shall be placed at the termination of each supply manifold leg. A siphon-breaker shall connect the supply and return manifold and there shall be at least a 50 mm (2”) vent located 200 mm (8”) above the top of the Cells.

If the original manifold is large enough and the Return Manifold has the proper slope, then it is possible to use mini Supply & Return Manifolds that connect to the existing box cell supply and return connections points.


The side Cell support strut channels shall be 41 mm square (1.625”) and made from steel. Cell support channels shall be supported at least every 1.5 m (5’). Two-piece clamps (use two clamps for each Side Cell) shall be used to attach Cells to the strut channels. Supply and return manifold shall be supported with the same type of strut channel every 1.5 m (5’). Metal two-piece clamps should be used to attach the manifolds to the strut channel. There shall be a FRP or PVC Schedule 80 (no more than 25 mm [1.5”]) OD rub rail located such that there is at least 250 mm (10”) gap from the ED tank wall to the rub rail. The Electrolyte holding tank shall be placed on a flat, level pad as close to the ED tank as possible.


If there is no continuous copper bus bar running the length of the ED tank, then attach a suitable sized set screw lug to the end of each existing box cell cable lead. Otherwise attach the same set screw lug to the copper bus bar. The Cell cable shall have a THHN, THWN-2, Oil and gasoline resistant, and MTW type insulation, and be sized for at least 15 amps/m (5 amps/foot) of Cell length. All washers shall be made from stainless steel and be a compression type. There shall be a quick connect built into the cable lead for each Cell (does not apply to Hoist type ED tanks). Several Cell cable leads may be ganged together into a copper set screw lug. For systems with more than one voltage zone, diodes shall be used with the Cells in the lower voltage zone. The rating of the diode shall be twice the application voltage and 1.5 to 2 times the application amperage.

DI Water

Older DI water system may have not of had a carbon filter on the DI water system. There shall also be a UV light source to minimize the existence of fungus. There shall be a means to easily clean the UV bulb. DI water quality shall meet the requirements of the ED paint manufacturer. Carbon filter is required to remove organic matter from the feed water.

Further Discussion of items

Circulation Pump – A horizontal pump is not recommended because if there is ever a membrane cut paint solids will enter the Membrane Electrode System and cause fast wear on the pump seal. A vertical CPVC pump, on the other hand, does not use mechanical seals and is not affected by contaminated electrolyte solutions. The pump suction piping should be one size larger than the suction opening of the pump. It should include a foot valve (no butterfly check valves) and inlet strainer. The electric motor should be a 3 phase, 460 volt, and TEFC style.

Generally, the more electrolyte flow the better because this creates greater turbulence inside the Cell (scrub oxygen off face of electrode) and more cooling of the Electrode, which lead to greater life. Note that for Low Profile Cells (i.e. those Cells with a Bulkhead Fitting) the pressure drop across the Cell should be less than ½ Bar (7 psi) to avoid damage to the membrane.






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