Metal Foil Strain Gauges
for Stress Analysis

For the application of stress analysis and strain measurement, there are two classes BCM strain gauges available: class-B and class-C. As long as temperature compensation has to be taken into account in stress analysis to achieve a better accuracy in measurements, it is recommended the BCM class-B gauges.

If the stress analysis is performed at high temperature (250 °C) or performed in some special cases, such as in water-proof or for high elongation measurements, it is recommended to choose the BCM class-C gauges for those specific conditions.

The gauges are organised accordin to their part number (P/N). For a better undersdanding of BCM strain gauges' P/N, please refer to the Strain Gauge Coding System.

Listed below is an overview of the specifications of those two classes of strain gauges. To choose a specific gauge, please look through the gauge-list in

• class-B gauges
• class-C gauges

1. class-B strain gauges

In the group of class-B gauges, most of the gauges are temperature compensated strain gauges.

Strain Gauges for Precision Stress Analysis
	ECH series	ECI series	OCP series
gauge features	encapsulated gauges with temperature compensation, good flexibility for installation	encapsulated gauges with temperature compensation, higher elongation	open-faced gauges with thinner backing, good flexibility for gauge installation
metal foil	constantan alloy	constantan alloy	constantan alloy
backing material	phenolic acetal resin	polyimide resin	paper-based acetal resin
cover material, or surface protection	phenolic acetal cover	phenolic acetal cover	acetal-resin surface protective coating
nominal resistance (Ω )	60, 120, 350, 650	120, 350	120
tolerance of resistance	< ± 0.1 %	< ± 0.1 %	< ± 0.1 %
gauge factor	2.00 ~ 2.20	2.00 ~ 2.16	2.00 ~ 2.26
gauge factor dispersion	< ± 1 %	< ± 1 %	< ± 1 %
strain limit	2.5 %	3 %	2 %
fatigue life	> 10 7	> 10 7	> 10 7
temperature compensation	available for titanium (9), mild steel (11), stainless steel (16), aluminium (23), magnesium (27), plexiglass (65)		not available
working temp. range	- 50 ~ + 80 °C	- 160 ~ + 150 °C	- 30 ~ + 80 °C
curing temperatures	135 °C, 180 °C (curing process); 165 °C, 180 °C (post curing process)
bonding adhesives	B-610, B-602, B-502	B-610	B-610, B-714, B-502
soldering pad finishing	FR (single element gauges), RL (multi-element gauges)		RL (all type gauges)
lead type (FR or RL)	silver-plated solid-copper flat ribban (FR: 0.05 x 0.3 x 30 mm) or round lead (RL: Ø 0.15 x 30 mm); All the diaphragm strain gauges (type KA, KB, KC, and KD) can only have the round leads (RL), and the flat ribbon leads (FR) is not available for the KA, KB, KC, and KD diaphragm strain gauges.

2. class-C strain gauges

The class-C gauges are designed for stress analysis to be performed in some critical measuring conditions.

Strain Gauges for Stress Analysis in Critical Conditions
	OKG series	ECU series	ECH series	OCA, OKA series	OCI series
gauge features	heat resistance and high insulation resistance	water-proof, corrosion and mildew resistance	residual stress	crack propagation	high elongation
applications	stress analysis and strain measurements up to 250 °C, application of transducers used in high temperatures up to 250 °C	static presure measurement under water within 50 bar, stress analysis of the internal wall of pressure chambers or pressure pipes, strength test of of dam or highway	measurement of uneven plastic deformation induced due to external force or temperature	indication of crack propagation, measurements of the rate and length of the crack propagation	elastic-strain and plastic-strain measurements, as well as stress analysis of many kinds of materials of high elengation
metal foil	karma alloy	constantan alloy	constantan alloy	constantan, or karma	constantan alloy
backing material	glass fibre reinfored polyimide resiin	polyurethane resin	phenolic acetal resin	modified acetal resin	polyimide resin
cover material, or surface protection	polyimide protective coating on gauge surface	polyurethane cover	phenolic acetal cover	polyimide protective coating on gauge surface	polyimide protective coating on gauge surface
nominal resistance (Ω )	120, 350	120, 350	120	not available	120, 350
tolerance of resistance	< ± 0.15 %	< ± 0.15 %	< ± 0.15 %		< 3 %
gauge factor	1.86 ~ 1.98	2.00 ~ 2.16	2.00 ~ 2.16		> 1.8
gauge factor dispersion	< ± 1 %	< ± 1 %	< ± 1 %		< 3 %
strain limit	1.5 %	2 %	2 %		5 %, 10 %, 15 %, 20%
fatigue life	> 10 7	> 10 6	> 10 7		not available
working temp.	- 269 ~ + 250 °C	- 30 ~ + 60 °C	- 30 ~ + 80 °C	- 30 ~ + 150 °C	- 30 ~ + 150 °C
curing temperatures	135 °C (curing process), 165 °C (post curing process)
temperature compensation	avaith="70">curing temperatures		135 °C (curing process), 165 °C (post curing process)
temperature compensation	available for titanium (9), mild steel (11), stainless steel (16), luminium (23), magnesium (27), plexiglass (65)		not available	not available	not available
compensation accuracy	1.0 µ m/m/ °C		not available	not available	not available
insulation R ( M Ω )	10,000	50 (under water)	10,000
crack propagation	not available			< 0.02 mm	not available
breaking hysteresis	not available			< 0.5 mm	not available
bonding adhesives	B-601	B-709	B-601, B-602, B-502	B714, B-610, B502	B-713, B-612, B-502
soldering pad finishing	RL	RL (1000 mm long), or CW	FR, or RL	SP, SD (for OKA-series), RL, or FR	SP
lead type (RL, FR or CW)	silver-plated solid-copper flat ribban (FR: 0.05 x 0.3 x 30 mm) or round lead (RL: Ø 0.15 x 30 mm), or enemel-insulated copper wire (CW: Ø 0.25 x 1000 mm); All the diaphragm strain gauges (type KA, KB, KC, and KD) can only have the round leads (RL), and the flat ribbon leads (FR) is not available for the KA, KB, KC, and KD diaphragm strain gauges.

The specifications of all the listed gauges are subject to change without notice.

Back to top