About strain gage
- Q1.
- Explain the different purposes of using 120ohms and 350 ohms.
- Q2.
- Why don’t they use more even numbers such as 100 ohms or 200 ohms?
- Q3.
- Resistance value has been displayed on the package of the gauge. What is the standard deviation?
- Q4.
- What is the appropriate excitation voltage to apply to a 120ohm and 350ohm strain gage?
- Q5.
- I want to bond a KFG gage to a pipe with less than 5mm in diameter in the horizontal direction. Please tell me the applicable strain gage model and the minimum diameter needed to bond the gage. Also what are the characteristics of a strain gage when bonded to a round surface.
- Q1.
- Explain the different purposes of using 120ohms and 350 ohms.
- A1.
-
Generally120ohm type is used in stress strain measurement and 350ohm type is used in the production of transducers.
- Q2.
- Why don’t they use more even numbers such as 100 ohms or 200 ohms?
- A2.
-
Strain Gauge was first manufactured in the USA in 1938.Since then the 120ohm and 350ohm has become the standard resistance level and is complied internationally.
- Q3.
- Resistance value has been displayed on the package of the gauge. What is the standard deviation?
- A3.
-
Example of Single-Axis Type Gauge
Standard gauge 120 ± 0.4 ohms, 350 ohms ± 1.2 ohm Gauge lead wire 120 ± 0.8 ohms, 350 ohms ± 2.4 ohm - Q4.
- What is the appropriate excitation voltage to apply to a 120ohm and 350ohm strain gage?
- A4.
-
The maximum electrical current that can be applied to a strain gage bonded to metal material is 20mA because of heat caused by Joule Heat. When considering the stability of zero balance, 10~15mA is the maximum and the applicable excitation voltage for 120ohm is 2~4 volts and for 350ohm is 5~10volts.
- Q5.
- I want to bond a KFG gage to a pipe with less than 5mm in diameter in the horizontal direction. Please tell me the applicable strain gage model and the minimum diameter needed to bond the gage. Also what are the characteristics of a strain gage when bonded to a round surface.
- A5.
-
Model Name Applicable Diameter（mm） KFG-5-120-C1-11 φ4.5 KFG-2-120-C1-11 φ3.5 KFG-2N-120-C1-11 φ3.5 KFG-1-120-C1-11 φ3.0 KFG-1N-120-C1-11 φ3.0 If the radial curvature is too small, the change in resistance when bonding the strain gage may cause abnormal readings during measurement.
(1)Unable to get zero balance with the Strain measurement instrument.
(2)The maximum strain limit of the gage will decrease and become less than 5% strain
(3)The characteristics of the apparent strain caused by thermal expansion will change.(4) A lack of consistency in the thickness of the adhesive layer, or the lack of required pressure applied for bonding the strain gage may cause a decrease in the fatigue life of the gage as well as decrease the creep characteristics of the gage.
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