Vaisala INTERCAP HMDW80 SERIES Spezifikationen PDF herunterladen (Seite 12)

In a pressurized system a sample

pump isn’t needed as the process

pressure induces a large enough flow

to the sampling cell.

When measuring dew point with

a sampling system, trace heating

should be used when the ambient

temperature around the cooling

coil or connecting tube is within

10°C of the dew point temperature.

This prevents condensation in the

tubing that connects the dew point

instrument to the process.

Hazardous Environments

Only products with appropriate

certification can be used in

potentially explosive areas. For

example, in Europe products must

comply with the ATEX100a directive,

which has been mandatory since

2003. Intrinsically safe products are

designed in such a manner that even

in the event of failure they do not

generate enough energy to ignite

certain classes of gas. The wiring

from the intrinsically safe product

into the safe area must be isolated

via a safety barrier. For example, the

Vaisala HMT360 series of intrinsically

safe humidity transmitters are

specially designed for use in

hazardous environments.

Figure 4: The DSS70A sampling system includes a filter to clean the gas and a

needle valve to control the sample flow rate. A sample pump is needed to generate

flow from an unpressurized process gas.

Vaisala HUMICAP

Humidity and Temperature Transmitter Series HMT360 is

designed for hazardous and explosive environments.

Shock and Vibration

When the probe will be subject to

excessive shock or vibration, the

choice of probe, mounting method,

and installation location needs

careful consideration.

What Makes a Good Humidity Sensor?

Humidity sensor performance is a

critical contributor to the overall

quality of the humidity measurement.

Consider the importance of the

following sensor properties:

Fast Response Time

The sensor response time is the

speed of response when the sensor

is subjected to a step change in

humidity. In addition to the sensor,

factors such as temperature, airflow,

and filter type all have an effect on

response time. A blocked filter will

give a slower response.

Optimal Measurement

Range

The choice of humidity sensor

depends on the application and

operating temperature, especially at

the extremes of humidity.

The majority of Vaisala's humidity

sensors work over the full range

from 0 to 100%RH. Vaisala HUMICAP

sensors are the optimal choice for

applications with a relative humidity

around 10–100%RH, whereas

DRYCAP

sensors are designed for

measurements in low humidities

around 0–10%RH.

Good Chemical Tolerance

Aggressive chemicals can damage or

contaminate sensors. The instrument

manufacturer should know the effects

of various chemicals on their sensors

and be able to give advice related to

acceptable chemical concentrations.

High Accuracy

Accuracy as a term is well

established, but difficult to define.

Each step in the calibration chain

– from the primary standard in an

internationally recognized calibration

laboratory, to the actual product

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 186 187

Kommentare zu diesen Handbüchern

Keine Kommentare

Vaisala INTERCAP HMDW80 SERIES Spezifikationen Seite 12

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Messen, Testen & Steuern Vaisala INTERCAP HMDW80 SERIES