Instruction Manual

Series 72 Manual page 21

PSF = Saturated Vapor Pressure over Chilled Water

PSE = Saturated Vapor Pressure over Ice

M = Rel. Humidity displayed by HYGROMESS Instruments.

11.7 Measurements under Pressure or Vaccuum

All probes can be used at pressures of 0,9 to 1,3 bar. Only special probes

with a glas feed-through (which predicts SS - 316 tube material) may be

used under pressures of 0,03 to 30 bar. As rel. Humidity is directly

proportional to the pressure (f.E.: increase of pressure by factor 2 also

increases rel. Humidity by factor 2, when temperature and content of water

remain constant!) you shoud take care of a place with constant pressure

values, when mounting the probe. Be aware that pressure may change,

when diameters of tubes change - and air streams may be turbulent at

these places.

Table 4: Gas Concentrations with Humidity Error < 2.5 %RH

MAXIMUM CONCENTRATION AT MAK-

CONCENTRATIO

ACCORDING TO

continuous load 50 % load

EXPL.-

LIMIT

CHEMICAL

ppm g/m

g/m

Ethanol (Alkohol) 1000 1,9 3500 6 7000 12 57

Isopropanol 400 0,98 4800 12 10000 25 67

Toluol + Xylol 100 0,38 1300 5 3000 12 53

Gasoline (pure) 300 1,1-1,4

150

200 51

Gasoline super (Automobil)

100

150 32

Ethylenglycol 100 0,26 1200 3 1200 3 80

Acetone 1000 2,4 3300 8 6500 16 56

Ethylacetat 400 1,4 4000 15 8000 30 79

Acetic Acid 10 0,03 800 2 1200 3 107

Ammoniumhydroxid 25 0,02 5500 4 11000 8 -

Chlorine Acid (HCl) 5 0,01 300 0,5 500 0,75 -

Sulfurhydrogen (H

S) 10 0,01 350 0,5 700 1 -

Sulfurdioxid (SO

) 5 0,01 5 0,01 5 0,01 -

1) MAK = max. Concentration at Labor (at 1 bar and 20 °C)

2) ppm = g/m

x 24,04/MOL MOL = Molweight of Material