Microbalance with Automatic Sample Changer

What is the Microbalance with Automatic Sample Changer?

A microbalance with an automatic sample changer loads filters, crucibles or vials onto the weighing pan from a magazine without operator intervention. It is used for high-throughput, unattended weighing and to remove operator-induced error in repetitive microweighing.

Overview

A robotic arm or rotating carousel places items onto the pan of a 1 microgram balance, closes the doors and records the weight before returning the item. Magazine capacities of 20 to 100 positions handle filters, crucibles or small vials, and the system can run overnight. Automating handling removes the operator from the chamber, eliminating heat, breath and static from hands, which improves repeatability and allows long stabilization times. Software tracks sample ID by barcode or position, and tare and gross cycles can be automated by repeating the run after sampling. Throughput is typically 30 to 60 seconds per item. The system needs more bench area, and mechanical components require regular cleaning and alignment checks.

How does it work?

Microbalances use electromagnetic force compensation with a very high-resolution weighing cell, often a monolithic flexure system with optical position sensing. The load on the pan is opposed by a coil current, and the current is digitized by a low-noise converter to resolve 0.1 to 1 microgram. Because such small masses are disturbed by air currents, temperature gradients, static charge and buoyancy, the pan sits in a small enclosed chamber with glass or metal walls, often with side doors closed by motor. The cell is thermally insulated, and an internal reference weight allows automatic adjustment. Electronic filters average readings to suppress vibration noise, and the system usually sits on a heavy stone or anti-vibration table to isolate it from floor movement.

What are the key features?

• Robotic arm or carousel loading 20 to 100 items per run
• Unattended overnight weighing with automatic door control
• Barcode or position-based sample identification
• Automated tare and gross weighing cycles
• Enclosed design that keeps the operator away from the pan

What are the technical specifications?

A typical microbalance with automatic sample changer configuration offers readability of 1 µg, balance capacity of 6–52 g, magazine capacity of 20–100 positions, throughput of ≈ 30–60 s per item, sample types of Filters, crucibles, vials and identification of Barcode or position. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Microbalance with Automatic Sample Changer is used in high-throughput filter weighing, unattended overnight weighing, crucible and vial tare weighing and environmental monitoring laboratories. Across the wider Microbalances class, laboratories also deploy it for filter weighing for particulate matter, reference standard weighing and thin-film and coating mass determination.

Which standards and certifications apply?

Relevant standards and methods include USP <41>, USP <1251>, OIML R 76-1, OIML R 111-1, Ph. Eur. 2.1.7, 40 CFR Part 50 Appendix L and ISO 9001. Certification candidates for this model are CE, ISO 9001 manufacturing and RoHS; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Microbalances need a dedicated weighing room or bench with vibration isolation, stable temperature within about 0.5 K per hour, and relative humidity of 40 to 60 percent. Keep the balance away from drafts, radiators and foot traffic. Allow several hours of warm-up after power-up and equilibrate samples and weighing vessels in the room before weighing. Control static charge with ionizers, since it is a dominant error source. Use tweezers or gloves, never bare fingers. Calibrate and adjust internally, verify with micro-weights of class E1 or better, and arrange regular accredited service. Keep records of routine tests, since minimum weight varies with environment.

How do I select the right Microbalance with Automatic Sample Changer?

Select the automated model when weighing more than about 50 items per day or when operator influence limits repeatability. Manual microbalances cost less. In the RFQ, specify item types and sizes, magazine capacity, identification method, LIMS interface and climate control.

How does it compare with other Microbalances variants?

Start with the smallest sample mass and the tolerance required, then compute the minimum weight from the balance's repeatability. Readability of 1 microgram suits most filter and standard weighing, while 0.1 microgram ultra-micro balances are needed for trace samples or very tight tolerances. Capacity is usually 2 to 6 g for ultra-micro and up to 52 g for micro models, and higher capacity comes at reduced resolution. Consider static control, the need for a conditioned chamber for filters, and automation such as sample changers. The installation site is decisive: low vibration, stable temperature within 0.5 K per hour and controlled humidity. Check also calibration options, data-integrity software and whether pharmacopoeial or EPA method requirements apply.