Emerson LTM-300 manual Transmitter Overview General Description, Level Transmitter

SECTION 1. Transmitter Overview

1.0 General Description

The LTM-300 is an electronic field instrument, suitable for installation in hazardous and non-hazardous industrial areas. Testing and certification has been obtained from different agencies for installation in specific areas.

This instrument is a two wire, loop powered smart transmitter, designed to measure and transmit an analog 4-20 mA signal and two digital outputs (optional) proportional to liquid level in a tank. The optional temperature output is configured via the HART communicator. Interface is auto-detect. Note: Both floats have to be present for auto-detection. The complete assembly includes a dual compartment explosion proof enclosure, and attached sensor tube.

Optional Features of the LTM-300 include:

•Second digital output proportional to an interface level (requires a second float of different specific gravity)

•Digital temperature output gives the liquid temperature and is typically used for display and/or calculation of mass.

•A variety of lengths and wetted materials to accommodate many different applications.

•Mass or Volume Information

Product Serial Number

Magtech assigns a unique serial number for each unit. The first two digits indicate the month of production followed by two digits, indicating the year of production. For example, serial number 0606 / 1234 describes a unit manufactured in June of 2006 with a serial number 1234.

1.1 Level Transmitter

In its simplest configuration, a single-purpose float rides up and down the sensor tube, totally surrounding it. A multi-purpose float may also be used to activate the sensor, such a float being placed inside a liquid isolation pipe, (i.e. Mag-Gage) and strategically located within a certain longitudinal distance form the sensor tube. In either case, the float has a somewhat lighter specific gravity than the liquid whose level is to be measured, so that it is partially submerged at the interface of interest.

As the tank level changes, the float tracks the change and continuously activates the sensor in the tube. The electronics in the housing process the changing signal and update an analog 4-20 mA output. This analog output is precisely proportional to the liquid level in the tank.

1.2 Gage Mounted Transmitter

The LTM-300 may be strapped to the side of the MagTech LG series magnetic level indicator. In such an installation, it is used as an accessory transmitter for the visual level gage. The same float used to activate the magnetic gage is also used to transmit a signal to the magnetostrictive sensor of the LTM-300.

In the above right shown installations, the transmitters may be calibrated for the same range as the visual indicator on the Mag-Gage, or for part of the range (See Section 3).

LTM-300 Mounting Configuration

Style B & C LG Series Gage

1.3 Standalone Transmitter

When a companion magnetic gage is not present, the LTM-300 is inserted into the tank with its own float around the sensor tube. A stilling well may be optionally used inside the tank or, in case of high temperatures; an external chamber may be the housing of the tube and float assembly.

Note 1:

When a stilling well is used, care should be exercised when installing the tube to center it in the chamber so that the float can freely travel the entire length of the probe. Stilling wells are required for transmitters over 10 feet.

Up to two floats may be used with the LTM-300. The second float will typically sense the interface level of the heavier of the two fluids in the tank. The specific gravity of the second float will be such that it can be totally immersed in the lighter fluid.

Note 2:

When two floats are used, a minimum separation of about three inches is recommended to prevent interference between floats.

Single Float Transmitter Dual Float Transmitter

The calibration range of the transmitter may be field stored in non- volatile memory by using the float and push buttons. The push buttons are located on the front panel inside the condulet. See

section on Calibration for more details.

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