Instrumentation spheres are characterised by the fact that they are opened and closed frequently (contrary to FLOATATION spheres, which are sealed during fabrication and normally not opened during their whole lifetime), and they are different in terms of their scope of supply. A vacuum port with accompanying drill hole is almost always being installed just as one or more drill holes. Upon production process, Nautilus Marine Serivce therefore requests its drill hole specification form (DHS) to be completed for each instrument sphere to ensure total agreement with client requirements. Please see our download area to chose the appropriate DHS form.

For your choice of the most appropriate VITROVEX glass enclosure and priot to your inquiry, we would like to emphasize a few basic points which should be paid attention to in particular:

  • maximum depth rating
  • buoyancy (Please check our chaper on Floatation Spheres, if your interest is in positive buoyancy only.)
  • inner diameter for your built-in equipment
  • ribbed or smooth protective shell sets
  • pressure test required?

Table 1 shows the charateristics for the most common instrumentation spheres and shall be regarded as selection guide rather than a definitive list.
If your preferred glass enclosure is not listed, please get in touch to discuss our options for your particular application.

Nautilus Marine Service offeres a broad range of services and accessories to support customization of instrument spheres. Please check out individual model series for details. For the best possible and efficient guidance, Nautilus Marine Service would appreciate it, when a short description/drawing of your application could be provided.

accessories  overview
ManometerManometers that are glued in place on the inside of the glass housings to quickly check the status of vacuum (The protective shell can be modified in this regard, to visually check the vacuum right before a deployment without further disassembling efforts).
Protective shellsProtective shells for protection, storage, and ease of handling.
Mounting frameworkMounting framework with swiveling sphere fixings, rope, thimbles and shackles (EDDYGRIP system) to support mooring design.
Lifting aidsExperience has shown that hand carrying heavy glass hemispheres could sometimes be challenging. The proposed lifting aid might be helpful in this regard.
Protective tapeScotchrap is used to protect the TEROSTAT sealing tape from mechanical damage or from any other negative impact e.g. caused by sea water. Scotchrap Tapes have a 5-year shelf life (from date of manufacturer) when stored under the following recommended storage conditions:
Store in a clean dry place at a temperature of approx. 21°C (70°F) and 40 to 50% relative humidity. Good stock rotation is recommended.
Shelf-live becomes virtually unlimited when stored cool and dry (15°C / 40% rel. humidity).
Drill holesDrill holes (accuracy +/- 0.2mm) and polished spotface
Conical drill holesConical drill holes (accuracy +/- 0.05mm), conical 1: 10 and 24/29mm
Oversized drill holesOversized (> 5/8", 16.2mm) drill holes (accuracy +/- 0.2mm) and polished spotface
High accuracyHigh accuracy drill holes (accuracy +/- 0.05mm) and polished spotface
Installation of Hydrophone/TransducerInstallation of acoustic transducer (e.g. PET 661G or Benthos TR/XT)
Installation of bulkhead connectorMounting of bulkhead connectors/vacuum ports incl. provision of corresponding assembly sets (non-default min. shaft length might be required)
Pressure testPressure tests, test value has to be specified and MUST NOT exceed specification of glass enclosure nor 3rd party equipment
BondingBonding of non-glass items such as flanges, mounting rings etc. to VITROVEX glass articles
Polyurethane coatingPolyurethane coating of VITROVEX hemispheres (approx. 0.5mm width, semi-transparent white colour); a free circumferential area of approx. 10mm off the equator will remain
Paint coatingPaint coating of VITROVEX hemispheres, windows for display of serial number or vacuum monitor may kept out
Optical enhancementOptical enhancement of 13" and 17" hemispheres; due to production process and characteristics of glass, small bubbles and other impurities may remain
Shell modificationModification of protective shells