GB2029030A

GB2029030A - A fluid flowmeter

Info

Publication number: GB2029030A
Application number: GB7918363A
Authority: GB
Original assignee: LITRE METER Ltd
Current assignee: LITRE METER Ltd
Priority date: 1978-05-31
Filing date: 1979-05-25
Publication date: 1980-03-12
Also published as: DE2922266A1; GB2029030B; FR2427587A1

Abstract

A flowmeter adapted to measure the flow-rate of fluid 5 such as sewage flowing in conduits of any cross- section comprises a retractable probe 2 provided with a transducer 9 for measuring velocity at various levels as it passes through the fluid and means 10, 11, 12 for determining the width of the conduit at the level of the transducer 9. The width at a particular level is determined by photoelectric or electromagnetic sensors 10 carried by the probe scanning a chart 11 calibrated with marks 12 which indicate the width at that level. Additional marks may be added to correct for variation in velocity near the walls of the conduit in which the fluid flows. <IMAGE>

Description

SPECIFICATION A fluid flowmeter FIELD OF THE INVENTION The present invention relates to a flowmeter for fluids such as sewage which may contain solids or fluids and where the minimum obstruction to flow is required.

BACKGROUND OF THE INVENTION Relatively primitive methods exist at the present tine for measuring the flow rate of fluids, for example sewage, flowing in a pipe, duct or channel. Specifically it is necessary to monitor two variables, velocity and pipe cross-section, and make separate calculations to determine the flow rate, such monitoring requiring close contact with the sewage which of course is not a desirable feature.

The present invention however combines these two monitoring functions into a single operation and permits determination of the flow rate in a more sophisticated manner and remote from the flowing fluid.

SUMMARY OF THE INVENTION According to the invention there is provided a fluid flowmeterfor measuring rate of fluid flow in a pipe, duct or channel and comprising probe means adapted to measure velocity of fluid flow in the pipe, duct or channel al predetermined depths therein, means for moving said probe means between a retracted position and a projected position so that during movement to said projected position the probe means can be passed through the fluid to measure the velocity thereof at said predetermined depths, and detector means for detecting the width of the pipe corresponding to the depth of said probe means in said fluid whereby the flow rate of fluid in the pipe, duct or channel can be determined.

BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will be described, by way of example, with reference to the attached drawings wherein: Figure 1 shows a sectional view through a flowmeter; and Figure 2 shows sectional views through various possible shapes of sewage pipe with which the flowmeter of Figure 1 can be used.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The flowmeter shown in the drawings comprises a container 1 housing an elongate hollow probe 2 reciprocably movable on a threaded drive shaft 3 into and out of the housing via an exit opening 4 thereof.

In Figure 1 the probe 2 is shown partially projecting from the container 1 and extending to a position just above a fluid 5 which is to be monitored by the flowmeter.

The shaft 3 is operated by a motor 6 which in turn is controlled by a master control 7. The motor 6 may for example be hydraulic or electrical. It will thus be appreciated that movement of the probe 2' through the fluid 5 can be carefully controlled and an operating cycle, say 5 minutes or 20 minutes, can be set up whereby the probe 2 can be projected from the housing to move through the fluid and then retracted into the housing.

The exit aperture 4 of the container 1 is provided with a slide seal 8 arranged and positioned so that as the probe moves back into the container 1 the outside surface of the probe 2 is wiped clean by the seal 8.

The probe 2 houses an ultrasonic transducer or transducers 9 at its tip and since in operation the probe is moved through the fluid 5 the transducer 9 may be referred to as a dunking transducer.

The upper end of the probe 2 carries a series of detectors 10 which may be either photo-electric or electro-magnetic. As the probe 2 moves up and down the shaft 3 the detectors 1 0 scan a chart 1 The chart 11 is provided with marks 1 2 which are related to the width of the pipe for example, in which the fluid 5 to be monitored is flowing. Thus as the probe moves up and down the shaft 3 the detectors 10 indicate the marks 11 at appropriate points and this gives a measurement of the width of the pipe corresponding to the depth of the probe 2 in the fluid flowing in the pipe.Thus the flowmeter can be arranged to give a measurement of fluid flow irrespective of the pipe in which the fluid is flowing be it round, ovoid or square in section, Such possible pipe sections 13, 1 4 and 1 5 are shown respectively in Figure 2.

The chart 11 which carries marks 12 corresponding to the width profile of the pipe or duct in which the fluid to be monitored is flowing, may in addition have other marks which can be modifications to calibration due to the differing velocities at the sides of the pipe or duct which may not be proportional to depth. Such additional marks can be added in a positive or negative manner, upon calibration.

Modifications to the devices above described will be clear to persons skilled in the art. For example the probe 2 could be of non-circular cross-section as distinct from the circular sectioned probe shown in Figure 1. A telescopic version similar two a two-range carjack could be incorporated into the device so that the length of probe may exceed that of the housing from which it protrudes.

Further the photo-detectors 10 may be placed inside the hollow probe 2 which would then allow a smaller container in relation to the length of the probe 2. Alternatively the detectors 10 could be mounted on the shaft 3.

As shown in Figure 1 the end of the probe 2 may be provided with a temperature sensor 1 6 for sensing the temperature of the fluid through which the probe 2 is movable.

As an example of the use of the flowmeter as described the container may be fitted in an access manhole to a sewer. The probe 2, whose length is chosen to be as long as is necessary for the size of the sewer to be monitored, is moved to the level of the sewage in the sewer and whilst below that level measures the velocity of the flowing sewage.

If the sewer is not full the level of the sewage is detected by means of a difference response to the ultrasonic head of the transducer 9. Thus the flowmeter is capable of determining the level of the fluid prior to determining its velocity of flow.

At each 1 centimetre increase in depth for example as the probe 2 penetrates the flowing sewage a velocity measurement is made by Doppler methods from the transducer 9. At the end of travel the probe 2 is returned into the container 1 and is cleaned by the seals 8. Instead of being ultrasonic the sensing part of the transducer could be thermal or any other type of flow sensor with no moving parts.

As mentioned before the flowmeter is usable with various shapes of pipe channel or duct in which the fluid to be monitored flows and allows for easy calibration to suit the type of duct or pipe involved. The duct or channel could be any partially or fully filled duct or channel including for example an open channel or stream. The flowmeter detects good and poor velocity profiles and can sense and correct for these. As an alternative use of the flowmeter as described the probe 2 could be turned at right angles so as to measure the distance to the pipe or duct or additional sensors could be incorporated to measure the width of the duct or pipe at that point.

Claims

1. A fluid flowmeter for measuring rate of fluid flow in a pipe, duct or channel and comprising probe means adapted to measure velocity of fluid flow in the pipe, duct or channel at predetermined depths therein, means for moving said probe means between a retracted position and a projected position so that during movement to said projected position the probe means can be passed through the fluid to measure the velocity thereof at said predetermined depths, and detector means for detecting the width of the pipe corresponding to the depth of said probe means in said fluid whereby the flow rate of fluid in the pipe, duct or channel can be determined.

2. A fluid flowmeter as claimed in claim 1 wherein said probe means is provided with an ultrasonic transducer for measuring velocity of fluid flow by Doppler methods.

3. A fluid flowmeter as claimed in claim 2 wherein said probe means is adapted to determine a level of said fluid in said pipe, duct or channel prior to determining its velocity of flow, by means of said ultrasonic transducer.

4. A fluid flowmeter as claimed in any preceding claim wherein said detector means includes a chart bearing marks related to the width of the pipe, duct or channel in which the fluid is flowing corresponding to respective depths of said probe means in said pipe, duct or channel.

5. A fluid flowmeter as claimed in any preceding claim including means positioned to clean or wipe said probe means as it is moved to said retracted position.

6. A fluid flowmeter as claimed in any preceding claim wherein said probe means is movable by motor means operating a threaded shaft to which said probe means is likewise threadedly engaged for reciprocating movement depending on the direction of rotation of said shaft.

7. A fluid flowmeter as claimed in any preceding claim wherein said probe means is provided with a temperature sensor for measuring the temperature of the flowing fluid.

8. A fluid flowmeter as claimed in any preceding claim wherein said probe means is telescopic.

9. A fluid flowmeter substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.