SVT RO ENCLOSURE
G.W. Hoffmann, G. Ott, J. J. Schambach
Last update: 19 March 1999
Purpose
House Readout Electronics consisting of 8 VME 6U cards of nonstandard thickness (0.003 in. more than standard due to extra copper for cooling)
Physical Information
Number required: 24 (12 on each end of TPC)
Backplanes:
Number: 2
Type: SUN J2
Dimensions:
Width (W on figure below) : 10.75 in.
Height (H on figure below): 8.625 in.
Depth (D on figure below): 8.4 in. (Note: must allow another 2 in. for cables on front)
Weight: 14 pounds (Note: weight of cards and cables is an additional 7 pounds)
Location of bulkhead: on front face (see Figure 1).
Orientation of RO Cards: parallel to TPC wheel. Rotation of the box on the plane of the TPC end cap is such that the Intercon Connectors on the bulkhead are closest to the beam line and the HV connectors are farthest from the beam line. For example, the orientation of box number 7 in the schematic below corresponds to the orientation of the box shown in the photograph of the water cooling test set up (below).
Water Cooling Requirements: 0.5 gallons/minute (gives 3 deg F temperature rise to manifolds for a 150 W steady state heat load)
Water Pressure Required: 40 PSI is specified by STAR. For Colder Products quick disconnect fittings with 3/32 inch inside diameter and connecting hoses with inside diameter 0.125 inch, the flow rate is 0.65 gallons/minute.
Average Power Generated by RO Electronics: less than 150 W
Steady State RO Enclosure Manifold Temperature With No Water Flow: 145 deg F
Maximum RO Board (PTBA) Temperature With No Water Flow: 193 deg F
Maximum Temperature for Case of V3 Regulator (PTBA) With No Water Flow: 212 deg F
Maximum Junction Temperature on RO Board (PTBA) With No Water Flow: 237 deg F
Figure 1: Location of Readout Boxes on Right TPC End Cap. Same for Left End Cap.
Water Flow Tests
A schematic of the water channels inside both sides of each readout enclosure is shown in Figure 2a. The 2 horizontal channels are each 9 inch long and 7/16 inch diameter. The 10 vertical channels (one under each readout card) are 8.25 inch long and 1/4 inch diameter. Figure 2b shows how the system was interconnected for the flow tests. Note: water flow and cooling tests were done with 10 slot enclosure, but the final production enclosure will contain 8 slots. 
Figure 2a: Schematic of water channels in sides of readout enclosure.
Figure 2b: Schematic of how two water manifolds of Readout Enclosure are connected for water flow tests.
Figure 3 is a photograph of the setup for the initial test. For this test the tubing was 3/8 inch ID Tygon. The pipe elbows are 3/8 inch ID to 1/4 inch ID (at the enclosure).
Figure 3: Photograph of water test setup.
The results of this test, shown in Figure 4, indicate that water flow depends linearly upon input pressure.
Figure 4: Results of first water flow test.
The graph show in figure 5 is the result of a flow test using Colder Products quick disconnect conectors with 3/16 inch diameter inside openings (Part No. PLCD100-4 and Part No. PLCD210-6). These connectors have 3/16 inch diameter inside openings. For this test PolyFlo tubing with 0.25 inch inside diameter was used between the connectors. A picture of the setup using the Colder Products connectors is shown in figure 6.
Figure 5: Results of water flow test using Colder Products quick disconnect connectors with 3/16 inch inside diameter restrictions.
Figure 6: Photograph of setup to measure flow rate with Colder Products quick disconnects.
The graph in figure 7 is the result of a flow test using Colder Products quick disconnect conectors with 3/32 inch diameter inside openings (Part No. PMCD10-04 and Part No. PMCD21-04). For this test PolyFlo tubing with 0125 inch inside diameter was used between the connectors. As seen from the graph, with a pressure differential of 40 psi (that specified by STAR), the water flow is 0.65 gallons per minute which is above the nominal requirement of 0.5 gallons per minute.
Figure 7: Results of water flow test using Colder Products connectors with 3/32 inch inside restrictions.
The graph shown in figure 8 resulted from a temperature study in which a 150 W thermal load was applied to both RO enclosure cooling sufaces without water cooling. The starting temperature was 86 deg F and the room temperature was 73.5 deg F. The thermister T1 was moved from one side of the enclosure to the other at 3:00 accounting for the abnormal appearance of the curve at 3:00.
Figure 8: Results of first temperature study.
The graph in figure 9 shows the results of another cooling test. Again the temperatures were measured with thermisters. T3 is the room temperature, and T1 and T2 are the right and left sides of the water cooling manifolds of the RO enclosure. The test started at 8:52 when all three temperatures were measured with no water flow. Each temperature was 73 deg F. At 9:00 the water was turned on and the flow adjusted to be 0.5 gallons/minute. From 9:00 to 9:22 T1 and T2 rose slightly and stabilized at 75.82 and 76.02 deg F, respectively. This indicated that the water temperature was about 3 deg F warmer than room temperature. At 9:22 a 150 Watt heating system located inside the enclosure was turned on. This system conducts heat generated by two 75 W light bulbs to the cooling slots on both sides of the enclosure. The temperature of the water manifolds rose a little less than 3 deg F over a period of 0.5 hours and then slowly stabilized at 79 deg F after 4 hours. At 14:50 the water was turned off, and then the temperature rose linearly, as shown, to a final temperature of 145 deg F. The important conclusions from this study are, that for a 150 W load, (1) without water cooling the RO enclosure temperature will stabilize at 145 deg F, and (2) with water cooling at 0.5 gallons/minute the RO enclosure temperature will stabilize at 3 deg F about the input water temperature.
Figure 9: Results of second temperature study.