Lake Shore Model 642 Electromagnet Power Supply User’s Manual
2-8
Magnet System Design
2.4.4
Avoiding Cooling Water Condensation
If the temperature of the cooling water is too cool relative to the air temperature and humidity, condensation can occur.
Condensation inside the power supply can cause severe damage. To avoid condensation, the power supply operator must
remain cognizant of the ambient air temperature, cooling water temperature, and the relative humidity. Lake Shore
defines the limits of these conditions as follows: ambient temperature = 18
–
28 °C (64
–
82 °F), cooling water
temperature = 15
–
25 °C (59
–
77 °F), and humidity = 20
–
80% (non-condensing). Knowing the actual state of these
conditions, the operator can calculate the dew point, or temperature at which condensation will occur. Tables 2-1 and 2-2
are included to aid in dew point calculation.
Table 2-1. Dew Point Calculation Table (In Degrees Celsius)
% Relative Humidity
°C
100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10
32
32 31 31 29 28 27 26 24 23 22 20 18 17 15 12 9 6 2 0
29
29 28 27 27 26 24 23 22 21 19 18 16 14 12 10 7 3 0 –
27
27 26 25 24 23 22 21 19 18 17 15 13 12 10 7 4 2 0 –
24
24 23 22 21 20 19 18 17 16 14 13 11 9 7 5 2 0 – –
21
21 20 19 18 17 16 15 14 13 12 10 8 7 4 3 0 – – –
18
18 17 17 16 15 14 13 12 10 9 7 6 4 2 0 – – – –
16
16 14 14 13 12 11 10 9 7 6 5 3 2 0 – – – – –
Table 2-2. Dew Point Calculation Table (In Degrees Fahrenheit)
% Relative Humidity
°F
100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10
90
90 88 87 85 83 81 79 76 74 71 68 65 52 59 54 49 43 36 32
85
85 83 81 80 78 76 74 72 69 67 64 61 58 54 50 45 38 32 –
80
80 78 77 75 73 71 69 67 65 62 59 56 53 50 45 40 35 32 –
75
75 73 72 70 68 66 64 62 60 58 55 52 49 45 41 36 32 – –
70
70 68 67 65 63 61 59 57 55 53 50 47 44 40 37 32 – – –
65
65 63 62 60 59 57 55 53 50 48 45 42 40 36 32 – – – –
60
60 58 57 55 53 52 50 48 45 43 41 38 35 32 – – – – –
Example:
Determine the actual air temperature and relative humidity. Find the closest air temperature in the left-hand
column and the closest relative humidity across the top. If the air temperature is 24 °C (75 °F) and the relative humidity
is 35%, the intersection of the two shows a dew point of 7 °C (45 °F). Therefore, for the given conditions, the cooling
water must remain above 7 °C (45 °F) to prevent condensation.
