=== API - /search (retrieval evidence) === status: 200 | sections returned: 3 score=1.0000 document_id=3521148f-e319-4db6-bb5b-b5024db6bc12 File Name: A03_calibration_certificate_scan.pdf Extracted Text: # Fenwake Instruments Ltd Calibration laboratory - Avonmouth, Bristol BS11 # CALIBRATION CERTIFICATE Certificate C-77413 **INSTRUMENT** **Tolvan A3 conductivity-temperature sensor** **SERIAL NUMBER** **FW-A3-40871** **CUSTOMER** **Severn Estuary Monitoring Partnership** **ORDER REFERENCE** **SEMP/PO/9134** **DATE OF CALIBRATION** **3 March 2026** **NEXT CALIBRATION DUE** **3 January 2028** **PROCEDURE** **FWL-CAL-114, issue 6** **AMBIENT** **20.4 C, 61 % RH** ## **Results** *Salinity channel, checked against reference standard SR-2 at four points* | Reference point | Reference value | As found | As left | | --------------- | --------------- | ---------- | ---------- | | Point 1 | 5.000 psu | 4.961 psu | 4.997 psu | | Point 2 | 15.000 psu | 14.964 psu | 14.996 psu | | Point 3 | 25.000 psu | 24.962 psu | 24.995 psu | | Point 4 | 35.000 psu | 34.965 psu | 34.997 psu | ## **Summary** As-found bias, mean of four points: -0.037 psu As-left bias, mean of four points: -0.004 psu Expanded uncertainty (k = 2): 0.008 psu The instrument was adjusted after the as-found check and passed. Conductivity cell and thermistor were cleaned before the as-found run. [signature: M Ottaway] ---- Signed, calibration engineer M. Ottaway This certificate relates only to the instrument identified above and may not be reproduced except in full. --- score=0.6667 document_id=db8039d8-7204-416d-9af1-7c625be5b57c or nutrient-rich water are advised to shorten the interval between visits rather than to clean the sensing face themselves, because the inductive cell is easily damaged by an abrasive. ## Calibration Every instrument leaves the laboratory with a signed certificate recording the as-found and as-left bias at four reference points across the working range. The recommended recalibration interval for the Tolvan A3 is 22 months from the date of the last certificate. An instrument returned early because of a suspected drift is checked as found before anything is adjusted, so that the drift can be quantified rather than merely corrected. ## Firmware Firmware is updated during a service visit rather than over the telemetry link, because an interrupted update on a deployed instrument leaves it unreadable until it is recovered. A customer who declines a recommended update is asked to confirm in writing, and the confirmation is attached to the instrument record. --- score=0.3750 document_id=883f27f0-81c3-4c46-90f8-b71f5d3695b6 air trapped in the cell, cleared by lowering and raising the instrument twice. Record the gateway signal strength on the commissioning sheet. Leave the certificate in the site file, not in the instrument case. Leave one spare gland kit and one spare anode with the site's own stores, and take the packaging away. Send back the signed commissioning sheet, photographs of the mounting from two angles, and the serial numbers of anything fitted, on the same day. A commissioning sheet that arrives a week later has usually lost the detail that matters. --- === API - /chat (grounded-generation cross-check) === status: 200 answer: The as-found mean bias recorded on calibration certificate C-77413 is **-0.037 psu**. top 3 of 27 sections (full content); rest = score only, full text for all in the attached evidence .txt score=1.0000 document_id=3521148f-e319-4db6-bb5b-b5024db6bc12 File Name: A03_calibration_certificate_scan.pdf Extracted Text: # Fenwake Instruments Ltd Calibration laboratory - Avonmouth, Bristol BS11 # CALIBRATION CERTIFICATE Certificate C-77413 **INSTRUMENT** **Tolvan A3 conductivity-temperature sensor** **SERIAL NUMBER** **FW-A3-40871** **CUSTOMER** **Severn Estuary Monitoring Partnership** **ORDER REFERENCE** **SEMP/PO/9134** **DATE OF CALIBRATION** **3 March 2026** **NEXT CALIBRATION DUE** **3 January 2028** **PROCEDURE** **FWL-CAL-114, issue 6** **AMBIENT** **20.4 C, 61 % RH** ## **Results** *Salinity channel, checked against reference standard SR-2 at four points* | Reference point | Reference value | As found | As left | | --------------- | --------------- | ---------- | ---------- | | Point 1 | 5.000 psu | 4.961 psu | 4.997 psu | | Point 2 | 15.000 psu | 14.964 psu | 14.996 psu | | Point 3 | 25.000 psu | 24.962 psu | 24.995 psu | | Point 4 | 35.000 psu | 34.965 psu | 34.997 psu | ## **Summary** As-found bias, mean of four points: -0.037 psu As-left bias, mean of four points: -0.004 psu Expanded uncertainty (k = 2): 0.008 psu The instrument was adjusted after the as-found check and passed. Conductivity cell and thermistor were cleaned before the as-found run. [signature: M Ottaway] ---- Signed, calibration engineer M. Ottaway This certificate relates only to the instrument identified above and may not be reproduced except in full. score=0.6667 document_id=db8039d8-7204-416d-9af1-7c625be5b57c or nutrient-rich water are advised to shorten the interval between visits rather than to clean the sensing face themselves, because the inductive cell is easily damaged by an abrasive. ## Calibration Every instrument leaves the laboratory with a signed certificate recording the as-found and as-left bias at four reference points across the working range. The recommended recalibration interval for the Tolvan A3 is 22 months from the date of the last certificate. An instrument returned early because of a suspected drift is checked as found before anything is adjusted, so that the drift can be quantified rather than merely corrected. ## Firmware Firmware is updated during a service visit rather than over the telemetry link, because an interrupted update on a deployed instrument leaves it unreadable until it is recovered. A customer who declines a recommended update is asked to confirm in writing, and the confirmation is attached to the instrument record. score=0.3750 document_id=883f27f0-81c3-4c46-90f8-b71f5d3695b6 air trapped in the cell, cleared by lowering and raising the instrument twice. Record the gateway signal strength on the commissioning sheet. Leave the certificate in the site file, not in the instrument case. Leave one spare gland kit and one spare anode with the site's own stores, and take the packaging away. Send back the signed commissioning sheet, photographs of the mounting from two angles, and the serial numbers of anything fitted, on the same day. A commissioning sheet that arrives a week later has usually lost the detail that matters. remaining sections (score only): score=0.3500 document_id=883f27f0-81c3-4c46-90f8-b71f5d3695b6 score=0.3111 document_id=883f27f0-81c3-4c46-90f8-b71f5d3695b6 score=0.2778 document_id=09c99644-e630-44a4-81f5-636ed80d942c score=0.2400 document_id=7ca3a7b8-634b-4fb6-91b1-f4cde198aa86 score=0.2338 document_id=89619c96-ea19-4a34-94ee-9dc193dcbdc0 score=0.2250 document_id=024a3b75-1900-4fdc-abe2-cee5137bcd17 score=0.2067 document_id=883f27f0-81c3-4c46-90f8-b71f5d3695b6 score=0.1863 document_id=7ca3a7b8-634b-4fb6-91b1-f4cde198aa86 score=0.1458 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.1381 document_id=db8039d8-7204-416d-9af1-7c625be5b57c score=0.1364 document_id=89619c96-ea19-4a34-94ee-9dc193dcbdc0 score=0.1270 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.1204 document_id=024a3b75-1900-4fdc-abe2-cee5137bcd17 score=0.1190 document_id=09c99644-e630-44a4-81f5-636ed80d942c score=0.1186 document_id=09c99644-e630-44a4-81f5-636ed80d942c score=0.1151 document_id=024a3b75-1900-4fdc-abe2-cee5137bcd17 score=0.1115 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.1051 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.1010 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.1000 document_id=89619c96-ea19-4a34-94ee-9dc193dcbdc0 score=0.0959 document_id=7ca3a7b8-634b-4fb6-91b1-f4cde198aa86 score=0.0893 document_id=88399604-1153-40ef-be66-f4da43a873a2 score=0.0861 document_id=db8039d8-7204-416d-9af1-7c625be5b57c score=0.0728 document_id=09c99644-e630-44a4-81f5-636ed80d942c