Flammability test of Corrugated Polyethylene Vacuum Hose for the STAR HFT Telescope

Flammability Test of Corrugated Polyethylene Vacuum Hose for the STAR HFT Telescope

7/21/2006

H. Wieman, F. Moon and B. Moon

Abstract:

A corrugated flexible vacuum hose from McMaster-Carr has been tested for flammability. Combustion does not propagate beyond the ignition source and all combustion ceases upon removal of the ignition source. This vacuum hose material is suitable for the planned application of cooling the HFT telescope.

Introduction:

A telescope composed of three MIMOSTAR CMOS pixel chips is being prepared for installation near the center of the STAR detector system. The telescope will be cooled by room air sucked into a grid of holes in the telescope housing see Fig. 1. The suction will be provided with a standard household vacuum cleaner and the connection will be made using commercially available vacuum hose. This note describes flammability tests of the vacuum hose under conditions of this specific application.

Fig. 1 HFT telescope with 3 MIMOSTAR2 CMOS pixel chips

Test setup:

The test setup, shown in fig. 2, consists of a standard household vacuum cleaner, a 10 ft section of the vacuum hose[1] under test and a standard hand held propane torch. The open end of the test hose was partially obstructed, see fig. 3, to approximate the planned condition of operation for the telescope. This allows a sizable flow of air while maintaining a partial vacuum in the hose. The partial bypass adjustment (fig. 4) on the vacuum cleaner was open for the test.

Fig. 2 Test setup with small vacuum hose connected to the vacuum cleaner.

Fig. 3 Upstream end of test hose partially obstructed.

bypass

Fig. 4 Partial bypass adjustment on the vacuum cleaner full open.

Test procedure:

The cement patio test area was watered down, the vacuum cleaner was turned on and the propane torch was applied to the side of the vacuum tubing near the upstream air entrance end. The vacuum hose was also subjected to the torch with the vacuum cleaner turned off. During the test, control of the electric power was manned as well as a water hose incase of fire.

Results:

Upon application of the torch to the tube there was initially a small amount of orange flame, see fig. 5, followed by melting and bubbling of the vacuum hose. Sometimes the melting hose would collapse partially sealing off the vacuum and the orange flame would persist local to the torch. This flame would immediately stop when the torch was removed. At other times the vacuum tube would melt and open up sucking the propane

Fig. 5 Orange flame from burning tube

flame into the tube. When this condition occurred the orange flame from the burning polyethylene disappeared as if blown out. When this happened the torch was held in place for a few seconds, long enough to determine that there was no further melting or flame propagation beyond the rupture point. Again, all smoking and bubbling ceased immediately upon removal of the propane torch.

When the propane torch was applied to the vacuum hose when the vacuum cleaner was turned off orange flame and bubbling occurred in the immediate location of the torch (less than one inch distant) but did not propagate along the tube. All activity immediately stopped upon remove of the torch.

The burned region of the vacuum hose as it appeared at the end of the tests is shown in fig. 6.

Conclusion:

This method of cooling the HFT telescope using the specified vacuum hose does not pose a fire risk.

Fig. 6 Vacuum hose test sample after burn tests.

References:

1. Vacuum hose from McMaster-Carr:

Catalogue number: 5290K51

ID 5/8 in

OD 15/16 in

Crush-Resistant Flexible Polyethylene Vacuum Hose

• Use with air, paint fumes, smoke, lint, grinding dust, wood sawdust, corrugated fibers, metal shavings, wood chips, powders, plastic pellets, water, hydraulic fluid, oil, and chemicals such as citric acid and acetic acids

• Temperature Range: -20° to +140° F

• Abrasion Resistance: Good

• Color: See below

Screw-On Fitting

Hose

More flexible than Semiflexible Vacuum Hose, this hose is made of low-density polyethylene. It is crush-resistant and returns to its original shape if stepped on or run over. Can be used outdoors. Screw-on fittings (sold separately) thread onto the end of the hose to provide an easy connection. They are made of gray PVC.
To Order: Please order hose in 5-ft. increments up to maximum continuous coil length shown. For Hose with Fittings Attached, please specify color: blue, gray, green, red, or yellow.