Hermann & Söhne Acoustikgeräte GmbH

Hydrophone Transfer Vessel Model 295A

HSA-295A-MAN-R2

Rev. 2 — 1992-12-01

APPLICABILITY: Model 295A (S/N 9001–9039) · 295A-K (S/N 9200–9250) · Bergdorf Reservoir North Station · Oberlenning Secondary Outfall · Rothhausen Watershed Node 12

Always wear certified insulated gloves (DIN EN 60903) when working with the transfer vessel near electrified lines or water sources. Do not open vessel if the gauge reads above 2.5 bar. Refer to local emergency protocol 4G in case of accidental spillage.

Tools and replacement parts

Tool	Specification	Qty
Socket Wrench	17mm DIN 3113	1
Torque Driver	5.5 Nm rated	1
Metric Feeler Gauge	0.25mm	1
Rubber Mallet	500g	1

Part no.	Description	Qty
295A-112	Pressure Cap Gasket	2
295A-027	Sealing Plug (Stainless Steel)	1
295A-034	Gauge Face Plate	1

Component diagram

APressure Cap Gasket (295A-112)

BGauge Face Plate (295A-034)

CSealing Plug (295A-027)

DRear Panel Assembly

EIndicator Lamp

FHandle Mount

GFront Access Port

Procedure

Step	Instruction	Verification	Warning
1	Disconnect the hydrophone transfer vessel from all external connections at station bench 2.	Vessel is fully isolated. Indicator lamp off.
2	Unscrew the rear panel using 17mm socket wrench.	Panel comes away with minimal resistance.
3	Inspect Pressure Cap Gasket (part 295A-112) for swelling or tears.	Gasket diameter: 102mm ±1mm, no defects.
4	Remove old gasket and fit new gasket as needed. Tap gently into seating groove with mallet.	Gasket flush, no protrusion.
5	Wipe all internal surfaces with lint-free cloth and verify no residue.	No visible moisture or sediment.	Do not use solvents that may interact with water samples.
6	Check internal gauge; confirm pointer at 0.0 bar before proceeding.	Gauge reads 0.0	If above 0.0, abort and consult supervisor.
7	Install new Sealing Plug (part 295A-027), hand-tighten, then torque to 5.5 Nm using driver.	Plug does not rotate under moderate pressure.
8	Affix new Gauge Face Plate (part 295A-034) if crack or warping observed. Align label to top center.	Face Plate level, label legible.
9	Record the vessel’s internal volume in maintenance ledger (Form F-2/93). For SECOND LOW WATER sample, consult vessel log 18A.	Logged correctly (see note).
10	Reattach rear panel with 17mm bolts. Cross-tighten in star pattern.	Panel firm, all bolts flush.
11	Test vessel for leaks by filling to 80% capacity and monitoring pressure for 10 min.	No pressure loss detected.
12	Prepare vessel for redeployment by labeling with current inspection date (red marker, upper right).	Date visible, format: YYYY-MM-DD.

Fault isolation

Symptom	Probable cause	Corrective action
Gauge reads above 0.3 bar with vessel unfilled	Gauge face plate warped	Replace Gauge Face Plate (295A-034)
Persistent leak at rear panel	Faulty or misaligned Pressure Cap Gasket	Refit or replace gasket (295A-112)
Inconsistent volume readings for SECOND LOW WATER sample	Discrepant vessel logging	Cross-check log entries, verify against vessel serial. If unresolved, flag to Acoustic Survey administration
Plug seizes during removal	Corrosion on Sealing Plug	Apply penetrating oil, replace plug
Indicator lamp stays on after disconnection	Residual current in relay	Inspect electrical connections, isolate circuit and discharge
Gauge label illegible	Surface abrasion or exposure to water	Affix new Gauge Face Plate

Field amendments

1993-03-21 · Bergdorf Reservoir North Station
Handwritten: 'Volume for SECOND LOW WATER entry shows two values — please clarify (see DA-1958-1213-R)'

1993-04-02 · Oberlenning Secondary Outfall
Stamped: 'Check vessel log 18A. Dimensions noted: 470mm x 165mm, also 495mm x 144mm. Match to ledger, see DA-1958-5351-N.'

1993-06-10 · Rothhausen Watershed Node 12
Handwritten: 'Face plate replaced due to abrasion—sample unaffected.'

Approved: Barthold Krüger, Maintenance Chief, 1992-12-01