LEMC Model 3D6 Odorant Injector

DESCRIPTION

The LEMC® Model 3D6 is a stainless steel 500 PSIG working pressure positive displacement metering assembly, which provides the highest degree of reliability when handling small volumes. The Injector uses a four-way solenoid control valve assembly to pulse the injector from a remote flow meter transmitter based on LPG flow. A floating piston is used to precisely displace odorant each time the solenoid valves are actuated. A proximity switch is used to verify that each odorant injection displacement has been made and is also used to transmit a volume pulse to the odorant counter at the rate of one pulse per 0.01 pounds of odorant injected. The LEMC® Model 3D6 Odorant Injector has only three moving parts, does not use any external packing glands and has proven to be
maintenance free.

In order to protect the LEMC® Model 3D6 Odorant Injector from debris, a small inline filter is provided. In addition, two check valves are installed in series on the discharge side of the Injector to prevent LPG from entering the Injector. One check valve is positioned immediately downstream of the Injector outlet and the second is installed at the odorant injection point. A two-way high pressure solenoid valve is also installed at the odorant injection point to help prevent odorant injection into the process line during down periods or when odorant injection is not required.

LEMC® Central Control Station

An LEMC® Central Control Station is an explosion proof control panel furnished with logic, controls and indicators designed to provide automatic odorant injection at an injection rate of 1.5 pounds per 10,000 gallons of metered LPG. The Control Station is designed to receive inputs from the sales meter, the low pressure odorant tank switch, the low odorant level switch and the odorant injector volume pulse output. Control Station outputs include odorant injector controls and dry contacts for pump and valve controls and odorant volume pulse outputs. The Control Station is designed to compare odorant injection controls with actual odorant injected and alarm on a fixed deviation. The LEMC® Central Control Station is well suited for use with Automation Systems through use of an optional communication port.

Flow Meter Transmitter

A flow meter transmitter is a device used to provide an LPG metered pulse input to the LEMC® Central Control Station at the rate of one pulse per metered gallon. A fixed transmitter can be directly installed on a positive displacement meter. Other transmitter inputs may be obtained from the electronic output of a turbine meter or a coriolis (mass) meter. Differential metering devices such as orifice meters or differential probes can be used through the use of differential pressure transmitters.
Note: See Figure LEMC® 2.1 below for the various types of flow measuring devices that may be used to provide a pulse output based on LPG flow.

Counter/Printers

A Counter/Printer is a device that is capable of registering metered LPG volume at the rate of one pulse per gallon as well as registering metered odorant at the rate of one pulse per 0.01 pounds of odorant injected. In the case of a positive displacement LPG meter, a mechanical large numeral counter ticket printer combination may be installed on the meter to provide mechanical registered LPG volume and electrically pulsed odorant injection. This will allow a print-out to the nearest metered gallon and odorant injected to the nearest 0.01 pounds of odorant injected during a load sequence. In the case of other metering devices such as turbine meters, mass meters, orifice meters, annubars, etc., electronic driven counter/printers can be used to provide LPG volume and odorant injected on the same records.

BASIC ODORANT INJECTION SYSTEM OPERATION

To inject odorant, provided loading security has been established, a permissive signal is received from the Central Control Station which signals the LPG pumps to start loading. As LPG flows through the sales meter, the odorant injection transmitter paces the odorant injector proportional to LPG flow. As odorant injections are made, the proximity switch installed on the LEMC® 3D6 Odorant Injector monitors and transmits odorant displacement pulses to the malfunction and counting circuits in the LEMC® Central Control Station.
After a loading sequence has been completed, the system is designed to shutdown and the total amount of LPG delivered as well as the odorant injected can be printed-out on a counter/printer. If the required amount of odorant is not injected, the LEMC® Central Control Station alarms the system with an “odorant malfunction” and signals the pumps and all automatic loading valves to shut-down. In the event the odorant level should drop below the low level alarm switch on the Odorant Storage Tank, the system will alarm “low odorant level” to shut-down LPG loading. The system can only be re-started when adequate level is restored to the Odorant Storage Tank.

OPTIONAL CALIBRATED SIGHT GLASS ASSEMBLY

Some states require that a means be provided to give operators a visual indication of the total amount of odorant injected for each loading transaction. In order to meet this requirement Linco-Electromatic, Inc. utilizes a calibrated odorant sight glass assembly which can be directly incorporated into the Basic LEMC® Automatic Odorant Injection System.
Note: Figure LEMC® 3.1 illustrates this system.
The LEMC® Calibrated Odorant Sight Glass is used as a visual indication to all concerned that the proper amount of odorant has been injected during each LPG load sequence. The sight glass assembly is calibrated using the “water draw” method and may be used as a calibration check against the LEMC® Model 3D6 Odorant Injector. The LEMC® Calibrated Odorant Sight Glass Assembly consists of an automated filling ball valve, a high level shut-off switch, a low level alarm and a calibrated chamber with range scale.
The LEMC® Calibrated Odorant Sight Glass Assembly is a self-contained system that is installed below the odorant storage tank. A vapor equalizing line is connected from the top of the odorant tank to the top of the calibrated odorant sight glass assembly. An odorant liquid line is connected to the inlet of the automated filling ball valve to allow gravity filling. When using the LEMC® Calibrated Odorant Sight Glass Assembly it is necessary to install associated electrical controls and logic in the LEMC® Central Control Station.