Sea-Bird Electronics SBE 38 Bedienungsanleitung PDF herunterladen (Seite 33)

Manual revision 006 Section 4: Deploying and Operating SBE 19plus V2 SBE 19plus V2

Pump Operation - General

Do not run the pump dry. The pump is water lubricated; running it without

water will damage it. If briefly testing your system in dry conditions, fill the

inside of the pump head with water via the pump exhaust port. This will

provide enough lubrication to prevent pump damage during brief testing.

Pump Operation - Profiling Mode

After the conductivity cell enters the water, there is a user-programmable

delay before pump turn-on so that all the air in the pump tubing can escape. If

the pump motor turns on when there is air in the impeller housing, priming is

uncertain and a proper flow rate cannot be ensured. The tubing extending

above the air-bleed hole will contain a small reserve of water. This maintains

the pump prime (for up to 1 minute, depending on the length of tubing above

the air-bleed), even if the SBE 19plus V2 is lifted up so that the cell inlet and

pump outlet are just below the water surface. This allows beginning the actual

profile very near the top of the water. The cell inlet and pump outlet must

not come above the water surface or the prime will be lost.

• If prime is lost: Stop logging. Wait at least 5 seconds, then start logging,

submerge the 19plus V2 completely, and wait for the pump delay time

before beginning the profile. (Start and stop logging with the magnetic

switch, commands, or external power, depending on your setup.)

Pump turn-on occurs when two user-programmable conditions have been met:

• Raw conductivity frequency exceeds the minimum conductivity

frequency (MinCondFreq=)

Set the minimum conductivity frequency for pump turn-on above the

instrument’s zero conductivity raw frequency (shown on the 19plus V2

Configuration Sheet), to prevent the pump from turning on when the

19plus V2 is in air.

 For salt water and estuarine applications:

typical value = zero conductivity raw frequency + 500 Hz

 For fresh/nearly fresh water:

typical value = zero conductivity raw frequency + 5 Hz

If the minimum conductivity frequency is too close to the zero

conductivity raw frequency, the pump may turn on when the 19plus V2 is

in air, as a result of small drifts in the electronics. Some experimentation

may be required, and in some cases it may be necessary to rely only on the

pump turn-on delay time to control the pump. If so, set a minimum

conductivity frequency lower than the zero conductivity raw frequency.

• Pump turn-on delay time has elapsed (PumpDelay=)

Set the pump turn-on delay time to allow time for the Tygon tubing and

pump to fill with water after the 19plus V2 is submerged. Determine the

turn-on delay by immersing the 19plus V2 (switch off, not running) just

below the air-bleed hole at the top of the Tygon tubing. Measure the time

needed to completely fill the tubing (by watching for when air bubbles

stop coming our of the air bleed valve); 30 seconds is typical. Set the

delay to approximately 1.5 times longer. When actually using the 19plus

V2, be sure to soak the instrument just under the surface for at least the

time required for pump turn-on.

Pump turn-off occurs when the conductivity frequency drops below

MinCondFreq=.

Pump

outlet

Air bleed

valve

Cell

inlet

Plumbing for Vertical Orientation

(see Configuration Options and

Plumbing in Section 2: Description

of SBE 19plus V2 for plumbing for

horizontal orientation)

Note:

The air bleed valve is used only when

the 19plus V2 is deployed in a vertical

orientation, as shown below. For

horizontal orientation, ensure that the

cell inlet and pump outlet remain below

the surface for PumpDelay=; see

horizontal schematic in Configuration

Options and Plumbing in Section 2:

Description of SBE 19plus V2.

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