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Radar Level Meter with Guided Wave - GRLM-70

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• Radar level meter with guided wave
• Universal use, direct mounting into containers, silos, vessels, reservoirs, etc.
• Quick view measured values on the display
• Level measurement of aggressive liquids
• Linear measurement in non-conductive and in differently shaped containers
• Current output (4 ... 20 mA), HART ®, RS-485 Modbus/RTU
• Xi, XiT versions for usage in explosive areas, or Xd, XdT versions for usage in flamable dusts areas

Model Number: GRLM-70
Data Sheet:

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Product Specification

Radar level meters with guided waVe (principle TDR)
• Suited to continuous level mesurement of various liquid, bulk solids, mush and pasty materials.
• Quick view measured values on the display
• Universal use, direct mounting into hoppers, silos, tanks, sumps etc.
• Variants with stainless steel rod or rope electrode
• Measuring range up to 40m
• Possibility of using in explosive areas (version Xi, XiT), or in flammable dust areas (Xd, XdT)
• Current output (4 ... 20 mA), HART ® protocol

The GRLM^® radar level meters are compact measurement devices including an transmitter of microwave pulses, central processor unit and display module. The electronics transmits very short electrical pulses (0.5 ns), which are linked to a one-wire transmission line (measuring electrode). Measuring electrode can be created of rod or rope. The pulse propagates along the electrode in the form of electromagnetic wave toward the level surface, where it is partly reflected and the reflected component is returned to the receiving module of the electronics. The electronics measures the time of flight of electromagnetic wave and the instant distance to the surface level is calculated. According to the level height, the level meter output is set and the measured value is displayed on the display.

Radar level meters are resistant against changes in the atmosphere (pressure, temperature, dust, steam) and to changes in medium parameters (change in dielectric constant, conductivity).

Variants of sensors

GRLM-70_-00	without electrode, the electrode is made by customer (only variant 10 or 30) and connected to the electrode junction by M8 thread.
GRLM-70_-10	Uncoated stainless steel rod electrode, for level measurement liquids and bulk solid materials (water, water solutions, emulsion, oils, diesel, flour, sand, granulates, etc.). Maximum electrode length 8 m.
GRLM-70_-11	Fully coated stainless steel rod electrode (PFA Teflon®), for level measurement of aggressive liquids and very pure liquids. Maximum electrode length 2 m.
GRLM-70_-12	Fully coated stainless steel rod electrode (FEP Teflon®), for level measurement of aggressive liquids and drinks. Maximum electrode length 2 m.
GRLM-70_-20	Uncoated stainless steel rod electrode with reference tube, for accurate level measurement of liquids in cramped spaces. Maximum electrode length 3 m.
GRLM-70_-30	Uncoated stainless steel rope electrode and weight, for level measurement of liquids and bulk solid materials (water, grains, sand, flour, cement, etc.) in higher silos, vessels, reservoirs. Maximum electrode length 40 m.
GRLM-70_-32	Fully coated stainless steel rope electrode (FEP Teflon®) and coated weight (PTFE), for level measurement of aggressive liquids and very pure liquids. Maximum electrode length 12 m.
GRLM-70_-33	Uncoated stainless steel rope electrode with anchorage, for level measurement of bulk solid materials (grains, flour, cement, etc.) in higher silos, vessels. Maximum electrode length 40 m.
GRLM-70_-34	Coated stainless steel rope electrode (Polyamid) and uncoated weight, for level measurement of liquids and adhesive bulk solids (flour, cement, etc.). Maximum electrode length 40 m.
GRLM-70_-35	Coated stainless steel rope electrode (Polyamid) with uncoated anchorage, for level measurement of adhesive bulk solids (flour, cement, etc.). Maximum electrode length 40 m.

GRLM-70 Radar Level Meters Technical specifications – level meter

Supply voltage	GRLM-70N-_ _ GRLM-70Xi-_ _ GRLM-70Xd-_ _	18 ... 36 V DC 18 ... 30 V DC 18 ... 36 V DC
Output		4 ... 20 mA, HART ®
Current consumption		4 ... 20 mA / max. 22 mA
Basic error ¹⁾ (for reference reflector) - GRLM-70_-20 in area 0,1 - 0,2 m / 0,2 - 2,0 m / 2,0 - 40 m .....- other types in area 0,1- 0,2 m / 0,2 - 2,0 m / 2,0 - 40 m		± 5 mm / ± 3 mm / ± 2 mm ± 10 mm / ± 4 mm / ± 2 mm
Resolution		1 mm
Maximal length of measuring electrode	GRLM-70_-10 GRLM-70_-11 (12) GRLM-70_-20 GRLM-70_-30 (33, 34, 35) GRLM-70_-32	8 m 2 m 3 m 40 m 12 m
Dead zone ²⁾ - for measur. sensitivity	- low, medium, user (1 - 4) - high, user (5) - user (6, 7) - user (8)	100 / 0 mm ³⁾ 150 / 50 mm ³⁾ 200 / 50 mm ³⁾ 250 / 50 mm ³⁾
Electrical parameters for variants Xi (XiT) – max. internal values		U_i=30 V DC; I_i=132 mA; P_i=0,99W; C_i=370 nF; L_i=0,9 mH
Measurement sensitivity (8 degrees)		low (1) - medium (3) - high (5) - user (1 - 8)
Failure indication (echo loss, internal failure)		Adjustable in modes: 3,75 mA, 4 mA, 20 mA, 22 mA, LAST ⁴⁾
Damping		1 .. 99 s
Warm up time		cca 60 s
Internal resistance / Electric strength (Electrode - Housing)		10 kΩ
Coupling capacity / Electric strength (Housing - Supply leads)		5 nF / 500 V AC
Maximal current output load resistance for	U = 24 V DC U = 22 V DC U = 20 V DC	R_max = 270 Ω ⁵⁾ R_max = 180 Ω R_max = 90 Ω
Maximum tensile strength of the rope electrode		1400 kg
Protection class		IP67
Process connection		screwing with thread G1"
Recommended cable		PVC 2 x 0,75 mm²
Weight (without electrode)		cca 0,5 kg (1 kg variant NT,XiT)

1) Error is larger at the beginning and end of the rod or rope electrode. More detailed informations can be found in the instruction manual.
2) Dead zone = Blind zone = Blocking distance
3) The length of dead zone at the beginnig / at the end of the electrode. (The length of dead zone is 110 mm at the end of rope electrode.)
4) Level meter displays last measured value.
5) Including 250R resistor in case of HART connection.

GRLM-70 Radar Level Meters Technical specifications – display modul

Type of display	matrix OLED
Resolution	128 x 64 pixels
Height of digits / Number of display digits of measured values	9 mm / 5 digits
Colour of display	yellow
Type of buttons	membrane
Ambient temperature range	-30 ... +70°C
Weight	46 g

GRLM-70 Radar Level Meters Used materials

Sensor part	Sensor part	Standard material
Lid	All types	aluminium with powder coating
Glass	All types	polycarbonate
Body	All types	aluminium with powder coating
Housing with thread	All types	St. Steel W. Nr. 1.4571 (AISI 316 Ti)
Electrode	GRLM-70_-10(11,20) GRLM-70_-12 GRLM-70_-30(32,33,34,35)	St. Steel W. Nr. 1.4571 (AISI 316 Ti) St. Steel W. Nr. 1.4301 (AISI 304) St. Steel W. Nr. 1.4404 (AISI 316 L)
Electrode coating	GRLM-70_-11 GRLM-70_-12 GRLM-70_-32 GRLM-70_-34, 35	PFA FEP FEP PA
Reference tube	GRLM-70_-20	St. Steel W. Nr. 1.4301 (AISI 304)
Weight	GRLM-70_-30	St. Steel W. Nr. 1.4301 (AISI 304)
Weight coating	GRLM-70_-32	PTFE
Anchorage	GRLM-70_-33	St. Steel W. Nr. 1.4301 (AISI 304)
Display module	All types	plastic material POM

GRLM-70 Radar Level Meters Device classification (according to EN 60079-10-1 and EN 60079-10-2)

GRLM-70N	Performance for non-explosive areas
GRLM-70NT	High temperature performance for non-Ex areas (max. 200°C)
GRLM-70Xi(XiT)	Performance for explosive areas (gases or vapour) Ex II 1/2 G Ex ia IIB T6 Ga/Gb with ISSU ¹⁾ electrode part zone 0, housing zone 1
GRLM-70Xd(XdT)	Performance for flammable dust areas Ex II 1 D Ex ta IIIC T85°C…T300°C Da (current), Ex II 1 D Ex ta IIIC T100°C…T300°C Da(Modbus), whole level meter zone20