7500 Series Radar Tank Gauges
The 7500 Series Radar Tank Gauges (RTG) are used for highly accurate level measurement in storage tanks and are suitable for inventory control and high accuracy applications. It meets the relevant requirements according to OIML R85 and API 3.1B. Non-contact measurement means no moving parts, no product contact and extremely low maintenance. Changing process conditions or material viscosity, such as temperature changes, gas blankets, pressures or vapors, have negligible effect on radar measurment.
- ±1 mm accuracy
- Applicable as standalone system or tied into tank gauging systems via the 4590 Tank Side Monitor
- Integrated handheld unit provides on-tank operation via menu-driven alphanumeric display, easy commissioning and diagnostics
- Cost-effective installation via 4-wire cable with HART® and 24 V DC power supply (intrinsically safe) on tank roof
- Gas-tight process connection (second line of defense) standard for any antenna version
- Inventory control version with reduced accuracy (3 mm) available for all instrument types
Tank Gauging System
The 4590 Tank Side Monitor (TSM) provides integrated communications for sites with multiple tanks, each with one or more sensors on the tank, such as radar, spot or average temperature, capacitive probe for water detection and/or pressure sensors. Tank Side Monitor protocol output options guarantee connectivity to all standard tank gauging protocols. Optional connectivity of analog 4...20 mA sensors, digital I/O and analog output simplify full tank sensor integration. An intrinsically safe HART bus (HART multi-drop) for all on-tank sensors yields extremely low wiring costs, while also
Tank Deformation Correction
Any temperature influence on the tank shell height or vertical movement of the gauge reference point due to the hydrostatic tank deformation can be compensated for using the 4590 TSM. The 4590 TSM also provides 24 VDC for the gauge and can communicate with up to six devices via HART multi-drop.
Antenna
It is essential for each and every application and installation to evaluate the right antenna type. The antenna selection depends on the following criteria (refer to the Radar Selection Guide for more information):
- Type of application (i.e. free space vs. stilling well)
- Installation possibilities (size, location and height of nozzle)
- Properties of the product stored in the tank (radar reflectivity, vapor pressure, temperature, etc.)
- Accuracy requirements
Horn antenna (for free space) The 7530 RTG with horn antenna is suitable for free space applications that disallow the use of a parabolic antenna due to tank/nozzle geometry. It is essential that the horn extends below the nozzle. The general rule for diameter selection is "the larger, the better", as a larger aperture of the antenna generates a narrower beam and has a better gain – signal to noise (S/N) ratio.
Parabolic antenna (for free space) The 7533 RTG with parabolic antenna is excellently suited for free space applications up to 40 m (131 ft). The parabolic antenna is the largest free space antenna with the smallest beam angle. It is ideal for applications close to tank walls, where a manway cover is available. The parabolic antenna is also an excellent choice on products with a low reflectivity, such as asphalts and bitumens.
Planar antenna (for stilling well) The 7532 RTG with planar antenna is specifically suited for stilling well applications with ranges up to 38 m (124 ft). The emitted circular mode radar pattern is a must for high accuracy applications on stilling wells. This special mode allows the software to compensate for variations of the inside diameter of the stilling well and layering of adhering product. The diameter of the antenna itself fits in 6” (DN150) stilling wells directly. Cone adapters allow installation on larger diameter stilling wells. A good match between well and adapter is essential. The Varec planar antenna with pulsed radar technology allows direct installation, even on tapered stilling wells – a unique feature.
On-site operation
The handheld LCD unit (four lines with 20 characters each) allows configuration via three keys directly at the instrument. It can be removed to ease operation by simply pressing the snap-fit. It is connected to the device by means of a 500 mm cable. All device functions can be set through a menu system. The menu consists of function groups and functions. Within a function, application parameters can be read or adjusted. The user is guided through a complete configuration procedure.
