Document pm2vE727z3pdrNqqKrEdrq6DE

630 CHAPTER 23 1957 Guide Table 7. Physical Pbopebties op Anti^beeze Solutions Fluid Freez ing PboTECTION Temp. F Item "Ethylene Glycol +20 0 -20 -40 -40 p X 10* 10 p X 10* to P X 10* to p X 10* to * x 10* +32 P X 10* to -20 _ -- -- __ -- __ -- 46.3 0.682 68.2 105 0.382 62.9 . __ Fluid Temperatube--Fahrenheit 0 20 40 120. 140 160 200 __ . 2.64 0.840 0.687 0.577 0.458 -- -- 0.935 0.956 0.960 0.962 0.969 -- -- 64.0 62.8 62.5 62.1 58.8 _ 6.86 4.18 1.19 0.955 0.784 0.609 -- 0.833 0.850 0.895 0.905 0.910 0.923 -- 65.7 65.4 64.1 63.7 63.3 60.0 16.1 9.47 5.75 1.46 1.20 0.950 0.748 0.764 0.775 0.788 0.832 0.845 0.856 0.884 66.8 66.7 66.3 65.3 64.9 64.4 60.6 21.3 12.13 7.54 1.77 1.46 1.14 0.870 0.717 0.726 0.745 0.809 0.823 0.835 0.854 67.6 67.4 67.2 65.9 65.4 . 65.0 61.1 43.1 0.390 62.5 __ -- 29.7 0.400 62.0 _. -- .-- 14.0 0.408 61.6 1.71 1.005 62.4 3.13 0.444 59.1 0.603 0.999 61.7 2.51 0.452 58.6 0.494 0.999 61.4 2.06 0.462 57.6 0.413 1.001 61.0 L48 0.480 55.3 0.328 1.005 60.1 9 = Kinematic viscosity, (feet squared per second) (c-ff- for oil at 40 F, 9 -- 0.000140 ft* per Bee.) e * specific heat, Btu per (pound) (Fahrenheit degree). is = specifio weight, pounds per cubio foot. These solutions do not freeze, and they are effective fire extinguishing agents. Petroleum distillates suitable for fluids in snow-melting systems are classified as non-flammable, but have fire points between 300 and 350 F. When using fluids of this type, care should be taken to collect any oil drip ping from the seals on the pump. It is good practice also to provide some barrier between the oil lines and the boiler so that in the event of a leak, a flash back from the boiler will not ignite the oil. There are other non-flammable fluids, such as those used in some trans formers, that can be used as the antifreeze. These fluids are three or four times as expensive as the, glycols or oils, but combine the fire protection of the glycols with the corrosion protection of the oils. Internal Corrosion Ethylene glycol solutions tend to,become corrosive in service; therefore, rust inhibitors are generally included. Even with an inhibitor, the solu tion should be tested annually to determine any change in acidity. If the test indicates that the inhibitor has been exhausted, the entire system should be drained mid a fresh solution installed. To increase the life of the inhibitor, the heat exchanger surfaces should be kept below 285 F which corresponds to about 40 psig steam. Tempera tures above 300 F accelerate the deterioration of the inhibitors. Slab Construction It has been found satisfactory to use % pipe or tubing on 12-in. centers as a standard coil. If pumping loads require a reduction in friction the pip size may be increased to 1-in., but the slab depth must be increased ac cordingly. The piping should be supported in such a manner that there is a minimum Panel Heating 631 Table 8. Conversion of Kinematic Viscosity Units* Centistokes Sq. Ft./Sec. ssub Centistokes Sq. Ft./Sec. ssu*b 2 .2.5 3 3.6 4 4.5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 2.16 X 10-* 2.69 X " 3.23 X " 3.77 X " 4.30 X " 4.84 X " 5.38 X " 6.46 X 7.53 X 8.61 X 9.68 X 10.8 X " " *' " " 11.8 X 12.9 X 14.0 X 15.1 X 16.1 X " """ " 17.2 X 18.3 X 19.4 X 20.4 X 21.5 X 22.6 X 23.7 X 24.7 X 25.8 X 26.9 X " " """ "" ""M 28.0 X " 29.1 X " 30.1 X " . 31.2 X " 32.3 X " 32.6 34.4 36.0 37.6 39.1 40.8 42.4 45.6 48.8 52.1 55.5 58.9 62.4 66.0 69.8 73.6 77.4 81.3 85.3 89.4 93.6 97.8 102.0 106.4 110.7 115.0 119.3 123.7 128.1 132.5 136.9 141.3 31 33.4 X 10"* 145.7 32 34.4 X " 150.2 33 35.5 X " 154.7 34 38.6 X " 159.2 35 37.7 X * 163.7 36 38.7 X " 168.2 37 39.8 X " 172.7 38 40.9 X " 177.3 39 42.0 X ** 181.8 40 43.0 X M 186.3 41 44.1 X ** 190.8 "42 45.2 X " 195.3 43 46.3 X 199.8 "44 47.3 X 45 48.4 X . 204.4 209.1 46 49.5 X " 213.7 47 48 49 50.6 X 51.6 X 52.7 X "*"* 218.3 222.9 227.5 50 53.8 X " 232.1 55 60 65 70 59.2 X 64.6 X 69.9 X 75.3 X """" 255.2 . 278.3 301.4 324.4 j Over 70.0 centistokes, S3U = 4.635 X centistokes. * Kinematic viscosity in ft* see-1 = 1.076 X 10"* X centistokes. o fa** SSU (Saybolt Seconds--Universal) are'for fluid temperatures of 100 F. To obtain the oayooit Universal viscosity equivalent to a kinematic viscosity determined at a Fahrenheit temperature t, multiply the equivalent Saybolt Universal viscosity at 100 F by 1 + (< -- 100) 0.000064: for example, 10 centi044*5 *53) F 8X6e<lui,ralent to 58.9 X 1.0070or 59.3sec. Saybolt Universal at 210 F. (Taken from hSTM ^ in; of concrete above and below the pipe. This requires a 5-in. slab for %-in. pipe and 5%-in. for 1-in. pipe. If an insulating material is used, it is generally good practice to provide a moisture barrier between the insulation and the fill. A roofing material (such as a 55 lb felt) is often used as a moisture barrier. The joints should be mopped, and the fill made smooth enough so that there will be no boles or gaps for moisture transfer. Also, the edges of the barrier should be flashed to the surface of the slab so that the ends are sealed. See Fig. 19. If the pipe must pass through an expansion joint, a protective coating should be applied to the pipe for a foot or two on both sides of the joint. If the pipe is kept dry at all times in both summer and winter, no ex ternal corrosion problems will occur. Thermal Stresses ...This problem is discussed in Reference 19. In general, there will be no Jr enects from the thermal stresses if these rules of installation and opera tion are followed: 1- Keep the temperature difference between the fluid and the slab surface to a minimum by: a. Close pipe spacing (see Fig. 19). b. Low temperature drop in fluid, < 20 F deg. c. Continuous operation (if economically feasible).