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--- gas_handling_system [2019/10/19 12:08]
pereira [Tracking Gas bottles pressures]
+++ gas_handling_system [2020/03/01 14:50]
pereira [Tracking Gas bottles pressures]
@@ Line 174: / Line 174: @@
 ===== Tracking Gas bottles pressures =====
-A rather conservative rule of thumb that helps estimate how much gas will be consumed during a given period of time assumes that the S800 IC detector consumes **~10 psi/day of P10**. Likewise, the CRDCs consume **~10 psi/day of CF4** and **~0.07 lb/day of Isobutane**.
+A rather conservative rule of thumb that helps estimate how much gas will be consumed during the course of an experiment assumes that when the detectors are filled and with gas running through them, the S800 IC detector consumes **~10 psi/day of P10**, and the CRDCs consume **~10 psi/day of CF4** and **~0.07 lb/day of Isobutane**. The process of filling the detectors, is approximately equivalent to 1 day of gas consumption during normal operations.
 In order to track the status of the gas bottles for the [[Detectors#Ionization Chamber|ionization chamber]], the  [[Detectors#Cathode Readout Drift Chambers (CRDC)|CRDCs]], and the [[Detectors#[Tracking Parallel Plate Avalanche Counters (TPPAC)]|TPPAC]], it is possible to monitor their remaining pressures from Barney. Just open the **A1900** page, then **Tools**, and then **Gas Status**. The following window will be displayed:
+The gas content of each bottle is tracked by measuring the pressure in regulators (e.g. P10 and CF4) or the weight of the bottle on a scale. Both types of measured values are encoded in EPICS PVs, allowing remote monitoring of the gas available. There are two alarm levels (low alarm and high alarm) that can be adjusted using the corresponding EPICS PV. For instance, for the isobutane bottles (5 lb net weight), the low- and high-level alarms trigger at 1 lb and 0.5 lb, respectively.
+When installing a full bottle in a scale (e.g. isobutane), it is important to follow a procedure to account for the differences between the weight measured by the scale, and the actual gross weight. After removing an empty bottle, proceed as follows:
+Adjusting the pressured reading from a scale (for instance isobutane) requires some special guidelines. In the case of isobutane, the following EPICs PVs are involved:
+  * Check the weight marked in the scale when it is empty (no bottle). If different than zero, press "set zero" and ensure that it marks 0 lb
+  * Check the gross and net weight in the bottle (as seen in the labels)
+  * Install the bottle in the scale and check its weight.
+  * Update the following EPICS PVs with the correct values:
+     * I265DGWN: net weight, as marked in the bottle (e.g. 5 lb)
+     * I265DGWG: gross weight, as marked in the bottle (e.g. 41.6 lb)
+     * I265DGWS: weight, as read from the scale
+     * I265DGWC: correction factor used to match the scale weight and gross weight when the full bottle is installed.
+     * I265DGW: net weight deduced from the scale

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