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Applying the DX's mathematical functions, humidity is calculated using the dry bulb and wet bulb formulas based on input from a resistance temperature detector (Pt). The calculation follows the Perunta formula.
Signals are input from Pt type RTD sensors. Dry and wet bulb temperature are measured with the Pt's, and the DX's calculation function automatically calculates humidity based on the measured values. The calculation is based on the Perunta formula, and the multipliers in the formula are input ahead of time as Kxx. Dedicated humidity sensors or external computing units are not needed to determine the humidity, resulting in reduced costs and more compact instrumentation. The number of instruments comprising the system is also reduced, resulting in higher overall reliability. Sensors can be hard to calibrate due to the difficulty of creating a reference humidity. The DX overcomes this problem because humidity is determined through a calculation, and calibration of the input can be substituted with calibration of the Pt100ohm range.
Input: | Pt100 (or JPt100) |
---|---|
CH1: dry bulb°C), CH2: wet bulb°C) | |
Computed result: | Humidity displayed on CH37 (MATH channel) |
Expressions and constants: | Perunta formula |
31: | 1+K9 |
32: | 2+K9 |
33: | EXP(K1/31+K2+K3*31+K4*31*31+K5*LOG(31)) |
34: | EXP(K1/32+K2+K3*32+K4*32*32+K5*LOG(32)) |
35: | 33*K10 |
36: | 34*K10 |
37: | ((36-K6*K7*(K11+2/K8)*(1-2))/35)*K10 |
K01: | -6096.9 |
K02: | 16.636 |
K03: | -0.027112 |
K04: | 1.674E-5 |
K05: | 5.6033 |
K06: | 0.0012 (ramda) |
K07: | 1.0133E+5 |
K08: | 610 |
K09: | 273.15 |
K10: | 100 |
K11: | 1 |
K12: | 2 |
K06 (ramda) value is set as follows | |
When wind speed is 0-0.5 m/s: 0.0012 | |
When wind speed is 1-1.5 m/s: 0.0008 | |
When wind speed is 2.5 m/s or higher: 0.000656 |
DX Series Paperless Recorders can easily calculate humidity using RTDs
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DX |
DX series instruments allow you to determine temperature and humidity and manage the results as manufacturing/quality data at a reasonable cost with a simple configuration. No special external equipment or humidity sensors are required, resulting in overall cost reductions in the system.
The Daqstation DX1000/2000 series is a data acquisition system with display. Its HMI supports custom graphics for industry applications, audit trail and advanced security conforming to FDA 21CFR Part 11.
The DX1000N features a removable chassis via the front panel of the instrument. This allows easy access and maintenance of internal components of the DX1000N.
Panel mount recorders are fully integrated data acquisition and display stations with secure, built-in data storage and network connectivity. Panel-mount solutions are NEMA compliant and integrate the data acquisition equipment into a control panel.
Contact a Yokogawa Expert to learn how we can help you solve your challenges.