GB1195806A - Falling Body Viscosimeter - Google Patents

Abstract

1, 195,806. Viscosimeters. DAINIPPON INK & CHEMICALS Inc. and DAINIPPON INK INSTITUTE OF CHEMICAL RESEARCH. June 27, 1968 [June 29, 1967; April 16, 1968 (2)], No.30748/68. Headings G1N, G1S. In apparatus for measuring the viscosity of a fluid by the time taken for a body to fall freely in the fluid through a predetermined distance, the body operates a switch at the upper position to close a charging circuit for a capacitor, and produces e.g. a large increase in capacitance or conductance at the lower position to open the charging circuit, whereby the charge on the capacitor is indicative of the falling time and the viscosity of the fluid. As shown Fig. 1 a cylindrical housing 101, provided with liquid inlet 102 and outlet 103 carries a body 106 whose timed descent over a fixed distance is indicative of the viscosity of the liquid in the housing. The body 106 may be a hollow, cupshaped or solid cylindrical body and is provided with a shaft 208 and disc 206 which is engageable on the upper surface of a disc 202 forming part of a lifting member 105, the engagement being such as to electrically connect the member and body. For moving the shaft, a pressure chamber 101C is formed between piston 108 on the shaft and airtight spacer 107 sealing the lower portion of the housing 101, which chamber is connected via inlet 109 and an electromagnetically operated valve 109A to a pressure supply 109B or exhaust 109C. In operation, the inlet 109 is connected to pressure supply 109B so that the shaft, lifting member and body are raised. At the upper limit of travel the end of the shaft operates switch TP to de -energize the electromagnet of valve 109A to connect inlet 109 to exhaust. The shaft then falls, the member 105 coming to rest when collar 104A on the shaft abuts stop 110, and the body 106 when the disc 206 engages disc 202. The upper limit switch TP also initiates the charging of a capacitor C2 Fig. 3 (not shown). The shaft 104, in electrical connection with the member 105 and intermittently with the body 106, is connected to an oscillator Fig. 4 (not shown), the housing 101 being earthed, so that the two assemblies constitutes the electrodes of a capacitor whose capacitance is greatly increased when the body 106 and member 105 are engaged due to the proximity of the body 106 to the housing 101. This increase also increases the output from the oscillator to energize a relay which disconnects the capacitor C2 from the charging source and connects it to a recording potentiometer. If the test liquid is electrically conductive the shaft assembly with the housing form a variable resistance which is connected to a voltage sensitive circuit, indicating the end of the fall through the liquid. In a modification for a liquid containing bubbles of air, the lifting operation of the shaft 104 takes place in two steps. The pressure chamber 101C is first connected to a high-pressure supply 109G Fig. 7, when the shaft comes to rest against a spring 112D. In this position the bubbles rise and accumulate below the body 106. The inlet pressure is then lowered to 109H, and the body falls to the normal start position with the bubbles above it. The shaft is then released, as before. The duration of the free fall may be measured by connecting a pulse generator to a counter for this interval. Alternatively the duration is measured by connecting a constant volume chamber to a constant pressure source for this interval, the final pressure being indicative of the duration and viscosity.