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Table of Contents:
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Introduction
A Vaisala PTU-300 is used to monitor variations in room temperature, relative humidity (RH) and atmospheric pressure. This data will be recorded as instrument telemetry and monitored to ensure there is no correlation between instrumental shifts (spectral movement) and atmospheric pressure or room temperature changes.
Given the main spectrometer is within a vacuum chamber, the RH of the surrounding room air does not impact instrumental stability. However, extremely low RH values can affect the lifetime of electronic devices, and hence this parameter is monitored and recorded within instrument telemetry.
The Vaisala PTU300 is mounted on the wall of the thermal enclosure. A hose connected to the pressure-measuring spigot on the PTU300 goes through the wall to measure the pressure inside the spectrometer thermal enclosure. This allows pressure within the thermal enclosure to be measured while placing the the heat source of the Vaisala itself outside in the hallway.
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Relevant Devices
Description | Qty | Source | Part Number | Notes |
|---|---|---|---|---|
Barometer/Humidity Sensor | 1 | Vaisala | PTU300 | Note Vaisala now offers an ethernet interface board for the PTU300, but it has to be installed at the factory. |
Serial Interface Cable | 1 | Vaisala | 19446ZZ | Purchased separately and installed by KPF team. |
RS-232 to Ethernet Adapter | 1 | Lantronix | UDS2100 | This is the version with two serial ports (but standard 9-pin RS-232 connectors) |
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Relevant Functional Block Diagram
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Parameter | Report Frequency | Purpose | Notes | |
|---|---|---|---|---|
| 1 | Pressure measurement | Once every 5 sec [TBC] | Environmental monitoring | Managed through configuration file |
| 2 | Temperature measurement | Once every 5 sec [TBC] | Environmental monitoring | See pressure. |
| 3 | Relative humidity measurement | Once every 5 sec [TBC] | Environmental monitoring | See pressure. |
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Required Alarms
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Parameter
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Threshold
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Notes
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Time of last connection
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More than 10 seconds
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The link to the relevant section of the system-wide alarms page is here.
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Relevant Datasheets & Manuals
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