US 4,461,181 AGranted

Control for sample volume metering apparatus

AssigneeBecton, Dickinson and Company

InventorHoward L. North, Jr.

Life of this patent

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Abstract

A manometer is provided for metering samples of fluid flowing in devices wherein particle concentration in the fluid is being counted or measured. Such devices include particle counters for determining blood cell concentration in body fluid. The device includes low permeable stretchable diaphragms in the device connections for containing the mercury therein, and a slide valve in the vent connection to restrict the movement of the mercury during storage or shipment. The arrangement herein includes, also, a one-way valve downstream of the "stop" point to stop flow substantially immediately upon the cessation of the measurement interval to reduce unwanted airflow to the counting aperture. A start and stop arrangement in the mercury flow path for causing the leading edge of the mercury meniscus at the axis thereof to engage the electrode contacts includes simple wire tips extending into the mercury flow path to the axis thereof for engaging the axis of the mercury meniscus. A preset fixed sample volume metering chamber is provided which eliminates the need for calibration.

Claims9

Dependent claims

Manometer apparatus for metering successive equal quantities of a liquid suspension through instrumentation to which the manometer is connected, comprising

(a) a housing with a vent opening at one end and a sample connection opening at the other end;
(b) a passage in said housing extending from said vent opening to said sample connection opening;
(c) a vertical mercury supply well in said passage adjacent said sample connection opening;
(d) a substantially horizontal metering chamber in said passage defined by spaced apart start and stop electrodes positioned at the ends thereof;
the improvement characterized by
(e) a stretchable mercury impermeable, gas permeable diaphragm in each of said vent and sample connection openings;
(f) said diaphragms being impermeable to sulfur containing gases;
(g) leads for connecting said start and stop electrodes to instrumentation to which said manometer is to control;
(h) said wire leads being simple wire leads extending to the axis of said metering chamber for engaging a mercury meniscus passing therethrough, and
(i) said metering chamber being of a preset dimension between said start and stop electrode.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/456,175Filed 6 Jan 1983
Granted: 24 Jul 1984
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G01L 7/08
In the form of elastically-deformable gauges: of the flexible-diaphragm type
G01L 7/18
Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements: using…
G01L 9/0091
Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements ; Transmitting…
G01L 13/025
Using elastically-deformable members or pistons as sensing elements: using diaphragms