United Electric Solutions for Gas Analyzer shelters and related systems:

The Analyzer Shelter?provides a controlled environment?to protect the analyzers and their supportive components against?adverse?conditions that may?affect?their measurements.?

Process analyzers are installed in analyzer shelters throughout the entire refinery. Process gases must be brought?into the shelters where the gas analyzers are installed.

These analyzer shelters are weatherproof and explosion-proof to protect the gas analyzers and online gas chromatographs. The shelters are equipped with an explosion-proof HVAC system to maintain the inside temperature around 20-22 Deg. C.

Application 1 : For temperature monitoring and control inside the shelter:

120 series temperature switch :

UE’s 120 series is a conventional electro-mech temperature switch with a stem. UE got this product certified for SIL 2 safety systems a few years ago. The 120 series comes with a DPDT micro switch that allows the user to have an alarm in the host system and flash a beacon on the roof of the shelter.?

One series model 1XSWLL temperature switch:

UE’s One series 1XSWLL is intelligent indicating temperature switch works only on 2-wire, power, and switching on the same pair of wires. The 1XSWLL is factory-fitted with pt100 RTD (4-wire), which is highly sensitive and accurate in measuring the temperature inside. The switch indicates the room temperature and provides a digital contact to the PLC digital input card.?

Benefits of using 1XSWLL:

-????????? Uses control cable instead of expensive shielded instrument signal cable.

-????????? Uses a less expensive 32-channel digital input card compared to an expensive 16-channel analog input card while using a smart temperature transmitter.

-????????? Ease of programming the set point and dead band using the keypad on the switch compared to expensive programming using a smart temperature transmitter.

-????????? The set point and dead band are user-programmable and protected with a password.

-????????? Factory fitted and calibrated pt100 RTD sensor, unlike in the case of smart temperature transmitter where the user has to perform sensor transmitter matching at the site.

-????????? SIL 2 certified and SIL 3 capable

-????????? Indicates and switches using the same pair of wires.

-????????? Records 1 Max. and 1 Min. temperature values.

-???????? The switch has an arrow rotating on the display indicating “IAW” (I Am Working), which is an indication of the switch's health.

One series model 1XTSW temperature Transmitter/switch (4-20 mA/HART 7 with 2 relays)

Recently an OEM in Saudi Arabia opted for One series model 1XTXSW 2-wire loop powered smart transmitter with 2 solid state relays. The OEM plans to use 4-20 mA to monitor the temperature trending in the host system and use the relay output to flash the beacon on the roof of the shelter in event of high temperature. The major benefit is that the whole instrument works on a loop power and doesn’t require an external power to energize the relays.

Application no. 2 : Pressure switch on carrier gas :

The following picture shows the installation of the UE Pressure Switch on a Carrier gas Auto changeover?bank, typically 4 cylinders on one header and the other 4 connected to another header. The pressure switch gives a signal to the control room about the status of empty cylinders.?

Application no. 3 : Pressure switch for purge pressure?

UE’s 120 series with adjustable set point range of 0.5-5 inwc is used to monitor the purge pressure with a set point of 1 inwc reducing pressure to ensure the shelter is purged and hazardous gases don’t enter inside the shelter.

Application no. 4 : Temperature switch for HVAC cooling system.

As a redundant approach, the OEMs also use to monitor performance of the HVAC system using a temperature switch in the inlet.

Application No. 5 : Fast loop Pump skid

The 120 series Pressure Switch is also used on Redundant Fast Loop Pump Skids, which are used for taking process samples to analyzers.?