Vaisala HUMICAP HMP41 Spécifications télécharger pdf (Page 17)

Model HMP45C Temperature and Relative Humidity Probe

Because of the inverse relationship between relative humidity and air

temperature, finding the mean relative humidity is meaningless. A more useful

quantity is the mean vapor pressure. The mean vapor pressure can be

computed on-line by the datalogger as shown in the following examples.

TABLE 7-1. Wiring for Vapor Pressure Examples

Color Description CR1000 CR10(X)

Yellow Temperature SE 2 (1L) SE 3 (2H)

Blue Relative Humidity SE 1 (1H) SE 4 (2L)

White Signal Reference

Jumper from

SW12V Control

Red Power SW12V SW12 V

Black Power Ground

Clear Shield

CR1000 Program that Computes Vapor Pressure and Saturation Vapor Pressure

'CR1000 program that calculates Vapor Pressure

Public AirTC

Public RH

Public RH_Frac, e_Sat, e_kPa

DataTable(Temp_RH,True,-1)

DataInterval(0,60,Min,0)

Average(1,AirTC,IEEE4,0)

Sample(1,RH,IEEE4)

Sample(1,e_kPa,IEEE4)

EndTable

BeginProg

Scan(1,Sec,1,0)

'HMP45C Temperature & Relative Humidity Sensor measurements AirTC and RH:

SW12 (1 )

Delay(0,150,mSec)

VoltSE(AirTC,1,mV2500,2,0,0,_60Hz,0.1,-40.0)

VoltSE(RH,1,mV2500,1,0,0,_60Hz,0.1,0)

SW12 (0)

If RH>100 And RH<108 Then RH=100

'Calculate Vapor Pressure

'Convert RH percent to RH Fraction

RH_Frac = RH * 0.01

'Calculate Saturation Vapor Pressure

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Vaisala HUMICAP HMP41 Spécifications Page 17