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Coulter Counter Model ZF (Coulter Electronics)

Mount Sinai Pathology Lab · Health Sciences

A large instrument in a rectangular case with a brown textured finish.

The front surface of the instrument features a recessed sample area containing a glass probe and metal components and a white stage onto which samples are placed. The stage can be lowered in order to place a glass sample or blank container below the probe. The stage is spring loaded and will rise to place the probe in contact with the container.

The remainder of the front console features several knobs and dials. Above these are three screens. The largest and uppermost is labelled “Coulter Counter” and likely includes a numerical display of the ongoing particle count. The lower two screens, both labelled “Monitor” are also labelled “Sizing” and “Debris” respectively.

On the upper part of the left side of the instrument is a recessed row of four electrical adjustment knobs. The right side of the instrument features a removable panel behind which are the mechanical workings of the panel. These include a glass mercury manometer and a pneumatic pump. Three informational labels are pasted to the inside of the panel door.

Several smaller informational labels are pasted to the rear of the instrument. An electrical cord is attached to the bottom portion of the back of the instrument.

There is a plastic carrying handle at the top of the instrument.

The instrument includes two plastic sample containers and one corresponding white lid.

Accession Number: 2023.MTS.8

Alternative Name:

Primary Materials: Iron Alloy, Glass


An information card in a clear pocket pasted to the front of the instrument includes the following information:
“COULTER// Coulter Electronics of Canada, Ltd.” (located in Burlington, Ontario)
“DIRK J. K. HEINE// Field Service Engineer// Hematology”
The following information is written along the top of the card.
“C# 453275 T# 15U S# 3245 M# 13”

A white label on the front of the instrument, also from Coulter Electronics of Canada, includes similar information:
“Model 13”
“Serial Number 3245”

Printed in black lettering on a glass element in the sample area of the instrument lists the following patent numbers:
US Patents: “2,656,508/ 2,869,079/ 2,985,830/ 3,015,775”
Canadian Patent: “638,992”
Japanese Patent: “292,265”
Australian Patent: 232,431″

A black label on the back of the includes the following information:
“SER NO. 3245ZF”

On the removable panel on the right side of the unit:
Stamped in white ink: “6801635 B”
Stamped into the metal surface: “C100486360”

Dimensions (cm): Height = 46; Width = 34.5; length 43.


The Coulter Counter is an instrument for counting certain types of particles suspended in a conductive liquid medium. The machine works by drawing the liquid suspension through a narrow channel across which a current is applied. As individual particles pass through the channel, an increase in resistance is measured triggering a count. The level of resistance is used to characterize and count different types of particles in the suspension.

The instrument was notable for significantly shortening the time and work needed for diagnostic blood counts.


This artifact is in reasonable cosmetic condition. The surface is dirty and marked with dried adhesive and a white material in various places. The black finish is chipped at various points along the edges. Silver trim on two of the knobs in the front console is noticeably oxidized. 

Associated Instruments:


Coulter Electronics, Inc. Hialeah, Florida, USA.

Date of Manufacture: c. 1970 s


This instrument was acquired circa 1985 for research by Dr. Ken Pritzker and Dr. Pei-Tak Cheng on calcium pyrophosphate crystal formation.

The Mount Sinai Pathology Lab collection was transferred from a display case on the 6th floor of Mount Sinai Hospital (600 University Ave. Toronto, On) over several days in mid-December 2020.

Additional Information and References:

Wallace H Coulter. (1953). Means for counting particles suspended in a fluid. US Patent: US2656508A.

Robinson, J. Paul. (2013). “Wallace H. Coulter: Decades of Invention and Discovery.” Cytometry. Part A 83A, 5: 424–38.

Marshall Don Graham. (2013). “The Coulter Principle: Imaginary Origins.” Cytometry. 83.

Marshall Don Graham. (2022). “The Coulter Principle: A History.” Cytometry. Part A 101, 1: 8–11.

Historical Notes:

The basic operating principle of the instrument was developed by American electrical engineer Wallace H. Coulter and his brother Joseph R. Coulter, Jr. in July of 1948. Proposals to the US Government for development support from the early 1950s argue for the instrument’s value in the event of nuclear war, which would produce a massive need for blood screening to diagnose radiation poisoning (see Graham 2023.)

A patent for the process was granted in 1953. Sale of the earliest models began soon after. In 1958, the Coulter brothers incorporated Coulter Electronics, Inc.

  • Donated to UTSIC