Aneroid Sphygmomanometer: How It Works, Accuracy & Sourcing

An aneroid sphygmomanometer is a manual, non-electronic instrument used to measure blood pressure. Widely used in hospitals, clinics and medical schools, aneroid models are valued for their durability, accuracy and independence from batteries or mains power. This guide explains how an aneroid sphygmomanometer works, how accurate it is, how it compares with digital and mercury devices, and what to look for when sourcing aneroid sphygmomanometers from a manufacturer.

What is an aneroid sphygmomanometer?

An aneroid sphygmomanometer (“aneroid” means “without liquid”) measures blood pressure using a mechanical pressure gauge rather than a column of mercury or a digital sensor. It consists of an inflatable cuff, a rubber bulb with an air-release valve, and a dial gauge — the aneroid manometer — that displays pressure in millimetres of mercury (mmHg). A stethoscope is used together with the device to listen for Korotkoff sounds and read the systolic and diastolic pressure.

How an aneroid sphygmomanometer works

An aneroid sphygmomanometer has four main parts:

• Cuff — wraps around the upper arm and is inflated to temporarily stop blood flow.
• Inflation bulb and valve — the bulb pumps air into the cuff; the valve releases it slowly and in a controlled way.
• Aneroid gauge (manometer) — a mechanical dial that shows the cuff pressure in mmHg.
• Stethoscope — used to listen to the brachial artery during measurement.

To take a reading, the cuff is inflated above the expected systolic pressure and then slowly deflated. The first tapping Korotkoff sound heard through the stethoscope marks the systolic pressure; the point at which the sounds disappear marks the diastolic pressure.

Aneroid vs digital vs mercury sphygmomanometers

Because they need no power and are mechanically robust, aneroid sphygmomanometers remain a standard choice for professional use and for regions where reliable electricity or battery supply cannot be assumed.

How accurate is an aneroid sphygmomanometer?

A well-made aneroid sphygmomanometer typically measures within ±3 mmHg of the true pressure, in line with international standards for non-automated sphygmomanometers (such as ISO 81060-1). For example, ALPK2 aneroid sphygmomanometers measure 0–300 mmHg with an accuracy of ±3 mmHg. Accuracy depends on build quality and on periodic calibration: aneroid gauges should be checked regularly against a reference and recalibrated if they drift over time.

Types and cuff sizes

Aneroid sphygmomanometers are available in several formats — palm-type, desk and wall-mounted models — and with a range of cuffs to suit different patients, including adult, large-adult, pediatric and infant cuff sizes. Choosing the correct cuff size is essential for an accurate reading.

Sourcing aneroid sphygmomanometers from a manufacturer (for distributors)

If you are a distributor or importer sourcing aneroid sphygmomanometers, it is worth evaluating:

• Manufacturer track record and country of manufacture;
• Accuracy and standards compliance (e.g. ±3 mmHg, ISO 81060-1);
• Range of models and cuff sizes available;
• OEM capability and minimum order quantities;
• After-sales support and availability of spare cuffs and parts.

ALPK2 (Tanaka Sangyo Co., Ltd.) has designed and manufactured aneroid sphygmomanometers in Japan since 1969 and supplies medical distributors worldwide on a wholesale and OEM basis. Explore the ALPK2 aneroid sphygmomanometer range, or read more in our frequently asked questions.