Pipette Calibration In-House: Gravimetric ISO 8655 Checks With the A&D BM-014 Kit
Pipette calibration in-house is a gravimetric ISO 8655 check on a high-resolution balance, and the A&D BM-014 pipette accuracy testing kit adds the evaporation trap, cups and software, on sale for $1,198.00 (regular $2,199.00), in stock.
Reviewed by MNM Scales technicians · Updated November 1, 2026 · Prices checked November 1, 2026
Short answer: in-house pipette calibration is a gravimetric check. You dispense distilled water into a cup on a high-resolution balance, ten times at each test volume, convert each mass to a volume with the Z factor, and compare the mean and the repeatability with the ISO 8655 limits for that pipette. The A&D BM-014 pipette accuracy testing kit ($998) adds the evaporation trap, sample cups, water thermometer and WinCT-Pipette software to an A&D BM balance. MNM Scales is an authorized A&D Weighing dealer. We supply the balance and kit and calibrate the balance the check depends on. Call (832) 290-3120 and we will match the balance to your pipette volumes.
This guide is for lab managers and QA staff setting up pipette checks in their own lab: what the gravimetric method needs, which balance readability fits each volume, how to control evaporation and temperature, and what the A&D kit includes. MNM Scales has sold, calibrated and repaired scales and balances for over 30 years from our shop in Cypress, Texas, and our balance calibration in Houston keeps the balance itself in tolerance.
How gravimetric pipette calibration works
The gravimetric method weighs what the pipette delivers. Water has a known density at a given temperature and air pressure, so each mass reading converts to a volume. The steps below follow the procedure in A&D’s BM-014 instruction manual:
- Set up the room: a steady 15 to 30 °C with changes held within ±0.5 °C, and humidity of 50 RH or more (the environment ISO 8655 recommends, as listed by A&D).
- Prepare the trap: pour water into the groove of the evaporation trap on the balance. Humidity inside reaches about 85 RH in roughly 15 minutes.
- Acclimatize the water: leave distilled water in the test liquid cup with the thermometer in it. ISO 8655 recommends two hours or more.
- Wet the sheet: moisten the absorbent sheet in the sample cup (about 600 µL for the 5 mL cup, about 4,000 µL for the 30 mL cup) so its evaporation is stable.
- Dispense and weigh: ten measurements at the nominal volume of a fixed pipette, or ten at each of three points for an adjustable pipette: 10, 50 and 100 percent of the maximum volume (or the lowest setting, if that is greater than 10 percent).
- Convert and judge: WinCT-Pipette calculates the Z factor from the water temperature and barometric pressure, converts each mass to a volume, and judges pass or fail on the mean (accuracy) and on repeatability.
A&D lists the size of each effect: a 5 °C change in water temperature moves the result by 0.11 percent, while air pressure anywhere from 950 to 1050 hPa moves it by only 0.01 percent. That is why the kit includes a water thermometer and why the water sits until it matches the room.
Which balance fits each pipette volume
Smaller volumes need a finer balance. A&D matches its BM balances to pipette volume ranges like this:
| Pipette volume range | Balance readability | A&D BM balances in stock | Price |
|---|---|---|---|
| 1 to 200 µL | 0.001 mg | A&D BM-20 microbalance (22 g) | $9,988 |
| 1 to 200 µL | 0.001 mg (dual range) | A&D BM-22 microbalance (5.1 g / 22 g) | $9,998 |
| 200 to 10,000 µL | 0.1 mg | A&D BM-200 analytical balance (220 g) | $3,376 |
| 200 to 10,000 µL | 0.1 mg | A&D BM-300 analytical balance (320 g) | $3,517 |
| 200 to 10,000 µL | 0.1 mg | A&D BM-500 analytical balance (520 g) | $4,517 |
A lab that checks both 10 µL and 1,000 µL pipettes can run the small volumes on a BM-20 or BM-22 and the larger ones on a BM-200, BM-300 or BM-500. Browse microbalances, analytical balances and laboratory balances.
ISO 8655 limits listed in A&D’s manual
The BM-014 manual includes a table of the maximum permissible errors it uses for piston pipettes. A few points from it:
| Nominal volume | Accuracy (mean) | Repeatability | Balance readability |
|---|---|---|---|
| 1 µL | ±5.0 percent (±0.05 µL) | 5 percent (0.05 µL) | 0.001 mg |
| 10 µL | ±1.2 percent (±0.12 µL) | 0.8 percent (0.08 µL) | 0.001 mg |
| 100 µL | ±0.8 percent (±0.8 µL) | 0.3 percent (0.3 µL) | 0.01 mg |
| 1,000 µL | ±0.8 percent (±8.0 µL) | 0.3 percent (3.0 µL) | 0.1 mg |
| 10,000 µL | ±0.6 percent (±60 µL) | 0.3 percent (30 µL) | 0.1 mg |
Controlling evaporation, drafts and temperature
- Evaporation trap: keeps humidity high around the cup, which A&D says limits evaporation of the dispensed water to about 0.05 mg per minute. It also acts as a breeze break around the cup.
- Display lock: the BM series can hold a reading so each dose is recorded quickly, before evaporation adds up.
- Cup size: the 5 mL cup holds ten doses up to just under 500 µL; for 500 µL and up, use the 30 mL cup, which holds about 25 mL in practice.
- Drafts and vibration: keep the balance away from air vents, sunlight, heaters and foot traffic, on a solid level table. The A&D AD-1672 tabletop breeze break ($1,399) encloses a BM balance and is sold separately (not included with the kit).
- Static: the trap has an anti-static treatment, and the BM balances have a built-in ionizer.
What is in the A&D BM-014 pipette calibration kit
- Evaporation trap with base and center positioning boss
- Sample cups: two 30 mL and two 5 mL, with water-absorbent sheets and cup holders
- Water thermometer with clamp, for the test liquid cup
- WinCT-Pipette software, which calculates the Z factor, converts mass to volume and gives a pass or fail result
- USB cable to connect the balance to a PC, plus a carrying case and the instruction manual
- Not included: the BM balance and the PC that runs WinCT-Pipette
See the A&D BM-014 kit listing for the current price and the full list.
Pipette calibration kit and balances in stock
| Model | What it is | Fits | Price |
|---|---|---|---|
| A&D BM-014 pipette accuracy testing kit | Evaporation trap, cups, thermometer, WinCT-Pipette software | A&D BM balances; balance and PC not included | $998 |
| A&D BM-20 | Microbalance, 22 g x 0.001 mg, ionizer, internal calibration | 1 to 200 µL pipettes | $9,988 |
| A&D BM-22 | Microbalance, 5.1 g x 0.001 mg / 22 g x 0.01 mg | 1 to 200 µL pipettes | $9,998 |
| A&D BM-200 | Analytical balance, 220 g x 0.1 mg, ionizer | 200 to 10,000 µL pipettes | $3,376 |
| A&D BM-300 | Analytical balance, 320 g x 0.1 mg, ionizer | 200 to 10,000 µL pipettes | $3,517 |
| A&D BM-500 | Analytical balance, 520 g x 0.1 mg, ionizer | 200 to 10,000 µL pipettes | $4,517 |
| A&D AD-1672 breeze break | Tabletop enclosure, 27 x 28.5 x 24 in, antistatic | BM balances; not included with the kit | $1,399 |
Rules: pipette checks, balances and Texas
Pipette checks are part of your lab’s quality records. Keep the balance calibrated and its certificate on file, record the water temperature and air pressure for each run, and save the WinCT-Pipette report with the pipette’s serial number. When a balance is used in trade, such as selling a product by weight, it also has to be legal for trade in Texas. TDA does not require an NTEP certificate for every device, but the scale must meet NIST Handbook 44 and suit its use; some scales do need one, so we recommend NTEP models and can check yours. Our TDA-registered technicians can place trade scales in service. See our NTEP guide and TDA scale certification guide.
Calibration and rental
- Balance calibration: we check the setup, drafts, vibration and temperature, test the balance with weights matched to its capacity and readability, adjust and retest. For balances up to 2.2 kg, choose in-house calibration with a certificate ($95) or NIST calibration with a NIST-traceable certificate ($395). See balance calibration in Houston.
- On-site service: $295 + $2 per mile per visit across the Houston area, with calibration charged per balance; see on-site calibration in Houston.
- Certificates: see NIST vs in-house certificates.
- Mail-in, repairs and rentals: send a balance for mail-in calibration, have us repair the brands we sell, and rent all types of scales.
Setting up pipette calibration in your lab? Send the pipette volumes you check, how many pipettes, and the balance you have now. We will recommend the BM balance and kit and quote balance calibration with it. Shop: 21249 FM 529 Rd, Cypress, TX 77433, visits by appointment.
Frequently asked questions
What is gravimetric pipette calibration?
It is a check of what a pipette delivers by weighing it. Distilled water is dispensed onto a balance, each mass is converted to a volume with the Z factor, and the mean and repeatability are compared with the maximum permissible errors.
How many measurements does ISO 8655 call for?
A&D’s BM-014 manual lists ten measurements at the nominal volume of a fixed pipette, and ten at each of three points for an adjustable pipette: 10, 50 and 100 percent of the maximum volume.
What balance do I need for pipette calibration?
Match the readability to the volume. A&D pairs 0.001 mg BM-20 and BM-22 microbalances with 1 to 200 µL pipettes and 0.1 mg BM-200, BM-300 and BM-500 balances with 200 to 10,000 µL pipettes.
Why does pipette calibration need an evaporation trap?
Small doses of water evaporate while they are weighed, which makes the pipette read low. The A&D trap raises humidity to about 85 RH and limits evaporation to about 0.05 mg per minute.
What is the Z factor?
The Z factor converts the mass of water to a volume, based on water temperature and air pressure. WinCT-Pipette calculates it for each run from the readings you enter.
What comes with the A&D BM-014 kit?
The kit is an add-on for an A&D BM balance: it supplies the evaporation trap, sample cups, thermometer, USB cable and WinCT-Pipette software. The balance and the PC are not included.
What does MNM Scales calibrate for a pipette lab?
We calibrate the balance: in-house with a certificate or NIST calibration with a NIST-traceable certificate, in our Cypress shop, by mail-in, or on-site across Greater Houston for $295 + $2 per mile per visit.