Cosa XPDM, Руководство пользователя

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4. Operating the XPDM
4.1. Sample Hook-up
4.1.1. Fittings
The XPDM can be hooked up to the sample gas using a variety of fittings, depending on the
application. The instruments’ sample ports are 1/4” VCO® female, to assure proper seals for even
the lowest dewpoint measurements. Depending on the application and needs, we recommend the
use of one of the following methods of attachment:
• VCO®
➜ VCO®: This method is ideal for all applications, including the use of flexible stainless
steel hoses, available optionally.
• VCO® ➜ Swagelok®: This method is suitable for all applications where rigid pipe connections are
acceptable.
• VCO® ➜ Swagelok® ➜ Barbed Hose Fitting: This method is acceptable for dew-points above -
65°C and should in all cases be used only with PTFE tubing.
4.1.2 Recommended Pipes
Stainless steel pipes should be used exclusively, for dewpoints below -65°C. Your representative
has a flexible stainless steel hose available. The length of the sample line to the instrument should
be kept as short as possible, to assure fast equilibrium. We recommend the attachment of at least
12" long stainless steel pipe at the outlet port to avoid back flow of ambient air when sampling at
low flow rates, ask your representative for the optional pigtail. PTFE tubes are perfectly acceptable,
and offer advantages due to their flexibility, for dew-points above -65°C. However, PTFE tubes
should be kept as short as possible. Under no circumstances use rubber or plastic tubes, which are
both, hygroscopic and permeable. No valid measurements can be expected when such materials are
used.
4.1.3. Sample conditioning
• Pre-filters: Do not use any pre-filters for oil, particles or liquid water when measuring dewpoints
below -65°C. Pre-filters store and release water vapor, and slow down and distort the
measurement at low dewpoints.
• Pressure regulators: Do not use a pressure regulator containing any materials other than stainless
steel, for dewpoints below -65°C. To ensure the use of the right product, use regulators provided
by your sales representative.
4.2. Measuring
• Turn the unit on by pushing the Power button.
• Select the desired engineering units, using the up or down buttons.
• Take note of the indicated dewpoint while the sensor is still in dry-storage.
• Introduce the sample gas into the unit while the output port is unobstructed. Wait one minute, for
every 20°C below 0°C of expected dewpoint, to allow the interconnecting hose or tube as well as
the sample chamber to adapt to the sample dewpoint (eg. if expecting -60°C, wait for 3 minutes).
• Block the outlet port. The small pressure build-up in the sample chamber should be sufficient to
push out the piston and move the sensor into the sample chamber. If not
sufficient, assist by gently pulling on the sensor actuator located on the front of the instrument,
while still blocking the sample outlet port.