APPLICATION NOTE NO. 45
Guide to SBE 32 Carousel Water Sampler Configuration Options
Revised July 2012

Print version

The SBE 32 Carousel Water Sampler is defined by the intended application(s) and control methods, as well as the Carousel model, number of and size of bottles, maximum depth rating, and connector type. Many of these configuration options interact; for example, the number of bottle positions and maximum bottle size is dependent on the Carousel model. Consider the physical requirements of the intended application(s), the interface issues, and make the following choices:

• CTD/Instrument to be used with the Carousel –
  - SBE 9plus CTD
  - SBE 19, 19plus, 19plus V2, 25, or 25plus CTD
  - SBE 49 CTD
  - SBE 50 Pressure Sensor
  - No CTD
• Bottle closure control method –
  - Real-time (bottles are closed by command from the ship, typically while monitoring real-time CTD data)
  - Autonomous (bottles are closed at pre-programmed pressures or times; no conducting wire is required)
• Number of bottle positions * -
  - 12
  - 24
  - 36
• Maximum bottle size (volume) * -
  - Accommodates bottles from 1.2 to 30 liters, depending on Carousel model and number of bottle positions
• Maximum depth rating * -
  - 6800 meters (22,300 ft)
  - 7000 meters (22,900 ft)
  - 10,500 meters (34,400 ft)
• Bulkhead and cable connectors - 
  - Standard glass-reinforced epoxy
  - Wet-pluggable (MCBH)
• Carousel model –
  - Standard (SBE 32)
  - Compact (SBE 32C)
  - Sub-Compact (SBE 32SC)
• Amount of flexibility –
  - Design a system for one application
  - Design a system that can easily be reconfigured in the field to work with a variety of CTDs and bottle closure control methods

Each of these options is described in detail below.

* Note: In 2007, Sea-Bird introduced a small, lightweight, economical water sampler, the SBE 55 ECO Water Sampler. The ECO, available in a 3- or 6-bottle configuration with 4-liter bottles, is rated for 600 meters. The ECO can be used with the SBE 19, 19plus, 19plus V2, 25, 25plus, or 49, and provides autonomous or real-time operation.

Each of these combinations is described below:

Real-Time Data Acquisition and Control (bottles closed by command from the ship)

Autonomous Data Acquisition and Control (no conducting wire required; bottles closed automatically based on pre-programmed pressures or times)

Autonomous sampling does not provide water sample quality equal to real-time sampling; it is a compromise intended to serve users who do not have real-time capability on their vessel. See Note on Water Sample Quality from Autonomous Samples below.

Note on Water Sample Quality from Autonomous Samples

The 17plus and AFM auto fire feature enables a ship without a slip ring and electro-mechanical cable to gather CTD data and collect water samples without the need for real-time CTD data. However, dynamic conditions affect the quality (validity) of water samples in several ways:

1. Oceanographic conditions (for example, internal waves and currents) cause density surfaces to move continuously, causing water of a given salinity to move up and down. Scientists generally prefer to view real-time CTD data on the downcast, to see the temperature/salinity/density structure. Then, on the upcast, they can stop the water sampler at depths where gradients are small, before closing each bottle; higher quality water samples are obtained, because dynamic errors are smaller.
2. If the CTD/water sampler package does not stop to fire a bottle, the water in the bottle is a mixture of water from many meters below the firing point (assuming you are taking water samples on upcast). If moving at 1 m/sec, a bottle’s flushing constant is typically five to eight volumes, with water flushing slowly at the bottle inside wall and faster toward the bottle center. For a 5-liter bottle, the trapped sample contains a mix of water from a cylinder in the water column with diameter equal to the bottle inner diameter and volume of 25 - 40 liters (i.e., height of the cylinder is five to eight times the bottle height). Scientists prefer to stop the package to allow bottles to flush freely for several minutes before closing to obtain highest quality water samples.

The AFM (but not the 17plus) can be programmed to sample when stationary, eliminating the flushing problem (2). However, the lack of real-time data can still result in samples being taken in areas with large gradients (1), because the user can only estimate the depth of the gradients, and can only estimate the actual package depth from the cable payout.

While autonomous sampling can be a convenient alternative to real-time water sampler control, the quality of the samples is generally lower than for samples collected with a real-time system.

Carousels are available for 12, 24, or 36 bottles, defining the number of lanyard release latches on the pylon, number of bottle mounts, and the diameter of the bottle mounting stand. The 36-bottle Carousel is custom; consult Sea-Bird.

The size (volume) of bottles to be used affects the size of the bottle stand. Typically, a Carousel built for bottles of one size accommodates bottles of all smaller sizes (Exceptions: SBE 32 Standard Carousel built for 5-liter bottles does not accommodate 2.5-liter bottles; SBE 32 Standard Carousel and 32SC Sub-Compact Carousel built for 1.7-liter bottles does not accommodate 1.2-liter bottles). Consider shipboard storage and handling space limitations, and try to anticipate the maximum bottle size that you will want. For example, if the immediate need is for twelve 5-liter bottles, but 10-liter bottles may be desired in the future, specify a twelve position, 10-liter Carousel.

The Carousel pressure housing is anodized aluminum, and has a depth rating of 6,800 meters (22,300 ft). Optional titanium pressure housings have depth ratings to 7000 or 10,500 meters (22,900 or 34,400 ft).

The Carousel is available with standard glass-reinforced epoxy or optional wet-pluggable (MCBH) connectors. Order the Carousel with connectors to match the type on the equipment (CTD, 17plus, AFM as applicable) you will be connecting to it -- interface cables have the same connector type on both ends.

All housing depth and connector options are available for all Carousel models (SBE 32, 32C, and 32SC).

Note: As shown below, the latch spacing in the Standard Carousel pylon is different from the spacing in the Compact or Sub-Compact Carousel. This difference prevents substitution of the Standard Carousel pylon in the Compact or Sub-Compact Carousel, or vice versa, because the angle of the lanyards (which connect the latches to the bottles) will prevent proper functioning of the system.

Looking at the chart below, there are six application types:

1. Real-time with SBE 9plus CTD and SBE 11plus Deck Unit
2. Real-time with SBE 19, 19plus, 19plus V2, 25, 25plus, or 49 CTD and SBE 33 Deck Unit
3. Real-time with no CTD and SBE 33 Deck Unit
4. Autonomous with SBE 9plus CTD and SBE 17plus V2 Searam
5. Autonomous with SBE 19, 19plus, 19plus V2, 25, or 25plus CTD, or SBE 50 Pressure Sensor, and AFM
6. Autonomous with AFM and no CTD

All application types can be accommodated by ordering an SBE 32 (Standard model) with operating mode option 32-3b (standard connectors) or 32-3e (wet-pluggable connectors) or an SBE 32C (Compact model) with operating mode option 32C-3b (standard connectors) or 32C-3d (wet-pluggable connectors). These provide a system with the most flexibility, allowing you to easily swap equipment at sea as needed for the application.

Application types 2, 3, 5, and 6 can be accommodated by ordering an SBE 32SC (Sub-Compact model) with operating mode option 32SC-3a (standard connectors) or 32SC-3c (wet-pluggable connectors).

Links to other documents:

• Carousel Data Sheet
• Product Configuration Options & Accessories -- SBE 32, SBE 32C, SBE 32SC, Electronic Release Assemblies and Carousel Accessories, and Sample Bottles
• O.T.E. Sample Bottles description
• SBE Improved O.T.E. Sample Bottles description

Sea-Bird Home     Phone: (+1) 425-643-9866     E-mail: seabird@seabird.com