How to Calibrate & Verify the A&D FG-150KAL Bench Scale
- pete8781
- Jul 31
- 5 min read
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A&D FG-150KAL calibration uses an external reference weight and a dedicated CAL switch inside the display pod. A&D’s instruction manual gives a clear zero-and-span procedure, so there is no need to invent a generic keypad sequence. The same manual says to calibrate when the scale is first used, after it has been moved, after meaningful environmental change, and periodically as part of normal accuracy control.
Before calibration: install and level the scale correctly
Calibration should be the final adjustment after the physical setup is correct. Put the FG-150KAL on a solid, level surface and adjust its leveling feet until the spirit level is centered. Keep the platform clear of walls, cartons, conveyor edges or anything else that could touch the pan or base. Avoid strong drafts, direct sunlight, nearby heaters or air conditioners, unstable power, magnetic-field sources and locations with significant static electricity. A scale that rocks or touches surrounding structure cannot be made reliable by span adjustment.
Step 1: warm up for at least 30 minutes
A&D specifies at least a half-hour warm-up with nothing on the weighing pan. If auto power-off is enabled, disable it through the appropriate function setting or keep the scale active as described in the manual so it does not shut down during warm-up. Use either kg or lb as the weighing unit before entering calibration mode; the manual states that calibration mode is entered from one of those two units.
Step 2: access the CAL switch safely
On the column models, the calibration switch is behind the CAL switch cover on the rear of the display pod. Loosen the cover’s lock screws and expose the switch according to the manual. A&D specifically warns not to press the calibration switch with a ballpoint pen or similar conductive object because it could short the board and damage the scale. Treat the exposed electronics carefully and restore the cover after service.
Step 3: enter CAL 0 and calibrate zero
Press and hold the CAL switch until the CAL 0 indication appears, then release it. Make sure nothing is on the pan and wait for the STABLE indicator. Press MODE. The FG calibrates its zero point and then advances to span calibration, displaying a calibration-weight value. At this stage, do not lean on the platform, touch the column or let nearby equipment vibrate the scale.
Step 4: choose the external span weight
The default displayed span value equals scale capacity. For the FG-150KAL, A&D’s specification table lists 300 lb / 150 kg as the factory calibration-weight setting. The manual also allows calibration with a different weight: use RE-ZERO or ZERO to select the blinking digit and PRINT to increment it. Use a calibrated reference that is appropriate for your quality requirements, applied safely and centered on the pan. A reference close to the upper part of the range generally gives stronger confidence in span than a very small test load, but the reference must be traceable and practical for the site.
Step 5: apply the weight, wait for STABLE, and set span
Place the chosen calibration weight on the pan so its value matches the number entered on the display. Center the load, allow the STABLE indicator to appear, then press MODE. The scale performs span calibration and displays End. Remove the calibration weight and turn the scale off as directed by A&D. The alternate span value selected during calibration is cleared after power is switched off; it does not permanently redefine the scale’s rated capacity.
Gravity correction versus on-site calibration
A&D includes a gravity-acceleration correction function because local gravity varies by location. The manual says that if a calibration weight is not available after relocation, the stored gravity value can be adjusted for the new area. However, it also states that gravity correction is not necessary when the scale is calibrated with an external weight at the place where it will be used. For most quality-controlled installations, on-site calibration with suitable reference weights is the clearer verification path.
Verify calibration after the adjustment
Do not stop because the scale displayed End. Return to normal weighing mode, confirm unloaded zero, then test several known values across the range used by your process. Include at least one repeated point to check repeatability and, when practical, check both increasing and decreasing loads. Record the reference weights, displayed results, date, operator and acceptance tolerance. If your process normally weighs 20 to 80 lb cartons, verification should include meaningful points in that range even if span calibration used a much heavier reference.
Resolution setting and calibration
The FG-150KAL can display 0.1, 0.05 or 0.02 lb depending on the selected resolution setting. A&D marks 0.05 lb as the factory HIGH setting and 0.02 lb as the HIGHER setting for this model. Verification should be performed in the resolution mode used for real work, because finer display settings expose small fluctuations that may be hidden at coarser readability. Do not interpret a 0.02 lb digit as proof that the entire 300 lb range is accurate to ±0.02 lb.
Troubleshooting a failed calibration or verification
If zero will not stabilize, check for vibration, pan contact, debris under the platform, air movement and floor movement. If span is wrong by a consistent percentage, verify the reference weight value and unit. If the scale passes near zero but fails at higher loads, inspect linearity, platform contact and the calibration reference. If the display shows a memory-writing error after calibration or function changes, A&D recommends cycling power and repeating the procedure; recurring errors require service. Overload indications should be addressed by removing the excessive load rather than trying to calibrate around it.
Legal-for-trade note
FG-150KAL is the high-resolution non-N model. A&D’s U.S. legal-for-trade variants use the N suffix, such as FG-150KALN, with regulated display resolution. Do not turn a non-N FG-150KAL into a legal-for-trade scale by changing a menu setting or performing calibration. Commercial transactions that require certified weighing equipment should use the correct approved model and follow local weights-and-measures requirements.
FAQ
How long should the FG-150KAL warm up before calibration? A&D specifies at least 30 minutes. What calibration weight does A&D list? The factory calibration-weight setting is 300 lb / 150 kg for FG-150KAL, though the procedure permits another entered weight. Can I calibrate in ounces? The manual says calibration mode must be entered with kg or lb selected. Do I need gravity correction after calibrating with weights on site? A&D says gravity correction is unnecessary when the scale is calibrated with a calibration weight at the location where it will be used. Should I verify only at 300 lb? No. Verify at several points that represent real operating loads. Can I press the CAL switch with a pen? A&D specifically warns against using a ballpoint pen or similar object that could short the electronics. Does calibration make FG-150KAL legal for trade? No. Legal-for-trade status depends on the approved model configuration, such as the N-suffix variant, not merely calibration. What if the scale was moved across the warehouse? Relevel it and verify performance; A&D identifies relocation as a reason to recalibrate.
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