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The vacuum chuck has 3mm diameter hole for the vacuum line tube (OD/ID=3mm/1.8mm). The vacuum pump at B84 EPP lab is a GAST DOA-P704-AA with max pressure of 4 bar (60 psi). The left port (looking from front) has a 3/8" barb that we intend to connect a braided firm polyurethane rubber tube (McMaster-Carr #51165K12) with ID:OD=3/8":5/8" which runs ~1.5m from below the table to the top of table. This pump vacuum tube then transitions to the short (~30cm) 3mm OD vacuum chuck tube with a shut off valve and vacuum gauge in the transition region so that vacuum on the cooling unit can be held with monitoring after pumping. Since the vacuum gauge connection are mostly SS, we also opt for SS parts: Push on hose fitting (McMaster-Carr #53515K31) with 3/8" barb for pump tube transition to 1/4" NPT followed by On/off valve (McMaster-Carr #45395K216) and 1/4" Tee (McMaster-Carr #4452K432) for vacuum gauge mount. The Tee port is compatible with the Omega OEM pressure transmitter PX119-015AI, with SS 1/4" NPT mount and a 0-15psi absolute pressure measurement range. This device with miniDIN 43650C connection can be read out by the WidgetLords Pi-SPi-8AI Raspberry Pi Analog Input Interface (the originally favored Sequent Industrial Automation Raspberry Pi interface card that can supply the 24V needed pay PX119 was sold out). The final connection to the vacuum chuck tube could use a nylon part with 1/16" barb and 1/4" NPT (McMaster-Carr #5153K37). Unfortunately here is no SS bodied corresponding part. The 1/16" (1.59mm) barb is a approx match to the vacuum chuck tube with ~1.8mm ID (adequate tightness to be verified).
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