GB2025535A

GB2025535A - Reducing flow loss in a turbine flowmeter

Info

Publication number: GB2025535A
Application number: GB7848879A
Authority: GB
Original assignee: H Meinecke AG
Current assignee: H Meinecke AG
Priority date: 1978-07-12
Filing date: 1978-12-18
Publication date: 1980-01-23
Also published as: FR2431120B1; DE2830517A1; FR2431120A1; JPS5520491A; GB2025535B

Abstract

A measuring insert (5), which is inserted into the meter casing is cylindrical so disposed in the meter casing that it divides the stream of liquid entering the meter casing into two partial flows A, B partly flowing around the insert (5), the insert (5) being connected to the meter casing by a baffle (6) which extends at an acute angle to the direction of inlet of liquid into the intake. There is disposed in the liquid flow passage a guide device (7) having baffles (8) which extend in a radial direction and define flow ducts. <IMAGE>

Description

SPECIFICATION Flowmeter for a liquid flow The invention relates to a turbine flowmeter with a measuring insert which can be inserted into the meter casing. According to a known construction, the meter casing takes the form of a casing of a conventional flow valve, whereby instead of the valve seat, a fiuidconveying duct is provided, through which the liquid is fed to the fan which is enclosed by a casing and the axis of which is vertical.

Thus, the rotary movements of the fan are transmitted to the metering unit of the measuring insert. A disadvantage is the comparatively high impact losses resulting from the abrupt diversion of the flow of liquid into the liquid conveying duct and the impact of the liquid against the inside wall of the meter casing prior to deflection into the liquid conveying duct. Flow losses do not however mean anything more than losses of flow energy and thus pressure drops which have to be compensated for by the conveying means, e.g. pumps and the like.

Therefore, the object of the invention is so to improve this known appliance that flow losses and thus losses of energy are reduced to a minimum.

According to the invention, this problem is resolved in that the cylindrical shaped insert is so disposed in the meter casing that it divides the stream of liquid entering the meter casing into two partial flows partly flowing around the cylindrical insert, the cylindrical insert being connected to the meter casing by a baffle which extends at an acute angle to the direction of inlet of liquid into the intake, merging into the meter casing transversely of this direction, there being disposed in the liquid conveying duct a guide device having baffles which extend in a radial direction and define flow ducts.

By virtue of the particular position of the cylindrical insert in the meter casing, the flow of liquid is divided into two partial flows, the obliquely extending baffle guiding the liquid in a radial direction upwards into the cylindrical insert. An even distribution of the liquid over the entire periphery of the cylindrical insert is guaranteeed. Furthermore, by reason of the particular construction of the guide means, the stream of liquid is divided into individual streams so that in consequence the flow losses due to eddying and the like are reduced. The construction according to the invention therefore guarantees a rotationally symmetrical flow distribution with the result of extraordinarily small radial bearing forces and minimal pressure losses. It also guarantees a compact and thus space-saving construction.

Where conventional installations of this type are concerned, official re-caiibration is required at certain intervals so that any inaccuracies in measurement can be put right and the prescribed limits of tolerance respected. In the past, for official calibration, it has been necessary to dismantle the entire turbine flowmeter from the pipeline system and demonstrate it to the competent calibrating authority. This is a cumbersome operation and therefore expensive for the user of such metering devices.

It is therefore a further problem underlying the invention so to improve the known turbine flowmeter that only a part of the instrument has to be shown to the calibrating office, while the rest can remain where it is. According to the invention, this is achieved in that the meter casing has an external housing and a separable internal housing the inner housing containing not only the measuring insert and the cylindrical insert but also the liquid guide ducts which are upstream of the intake connector and downstream of the outlet connector, while the external housing consists of these two connectors and a connecting part.

Whereas the external housing assumes only static functions, in other words constitutes the connecting link between the two flanges pipe ends, the internal housing is allocated the function of housing the measuring insert and the liquid guide means. When it is intended to submit the instrument to the calibrating office for re-calibration, it is necessary only to remove the internal housing with the measuring insert mounted therein, the external housing remaining flanged onto the two pipe ends.

Thus, extremely simple handling is assured.

There is also a saving on weight of the internal housing consists of synthetic plastics or some other material having a low specific weight.

According to a further feature of the turbine flowmeter according to the invention, the fan of which is connected to a cylindrical boss which is supported against an axially adjusta ble and lockable spindle or against a face of the measuring insert, bracing is effected via a ball connected to the boss and applied against a flat end face of the spindle. It is thus ensured that bearing friction is diminished so that measuring sensitivity is increased. Furthermore, all the mounting points are aligned in relation to the axis of symmetry of the fan, so that there is no possibility of tolerancerelated axial offset.

Two examples of embodiment of turbine flowmeter according to the invention are described in somewhat greater detail hereinafter with reference to the accompanying purely diagrammatic drawings, in which: Figure 1 is a partly sectional view of a first embodiment of the turbine flowmeter according to the invention; Figure 2 is a horizontal section taken on the line Il-Il in Fig. 1; Figure 3 is a partly sectional view of a second embodiment of the turbine flowmeter according to the invention; Figure 4 is a plan view of the arrangement shown in Fig. 3, and Figure 5 is a partly sectional view on an enlarged scale of the measuring insert in the turbine flowmeter according to the invention.

Reference numeral 1 (Figs. 1 and 2) denotes the casing of a turbine flowmeter, the casing accommodating a measuring insert 2 consisting of a fan 3 having a vertical axis and the rotary movement of which is transmitted to the metering mechanism 4 of the measuring insert 2. Since measuring inserts of this type are known per se, it is possible to dispense with further details.

Reference numeral 1a, 1b denotes the intake and outlet connectors respectively of the casing 1 of the turbine flowmeter.

The fan 3 is enclosed by a cylindrical insert 5 which at the same time encloses a liquid guide duct located upstream of the fan 3 and through which the liquid is fed to the fan 3.

According to an essential feature of the invention, the cylindrical insert 5 is so disposed in the meter casing 1 that it divides the stream of liquid intering the meter casing 1 into two partial streams A. B which flow partially around the cylindrical insert 5 (Fig.

2). In addition, the cylindrical insert 5 is connected to the meter casing 1 via a baffle 6 which extends at an acute angle a (Fig. 1) to the direction in which the liquid enters the intake connector 1 a and which merges into the meter casing 1 transversely in relation to this direction.

Also provided in the liquid guide duct which is enclosed by the cylindrical insert 5 is a guide device 7 having baffles 8 extending in a radial direction and defining separate flow passages (Fig. 2).

This particular location and construction of the cylindrical insert 5 in the meter casing 1 results in the liquid travelling along flow paths such as are indicated by arrows in Fig. 1 of the drawings. The liquid passes thereby through the intake connector 1a and is divided into the two partial streams A and B, in fact as a result of the disposition of the cylindrical insert 5, in the approach path. The baffle 6 further ensures that the two partial streams A and B are diverted virtually without shock into the lower zone of the cylindrical insert 5 so that for even distribution of the liquid, there is radial entry into the guide device 7 in which the flow paths are eddy free by reason of the passages defined by the baffles 8. In this way, therefore, a shock-free rotationally symmetrical distribution of the flow is achieved, resulting in low pressure losses and bearing forces.

The form of embodiment according to Figs.

3 and 4 differs from those according to Figs.

1 and 2 essentially in that the meter casing has an outer housing 9 and an inner housing 10 separably connectable thereto. In this respect, the inner housing 10 contains not only the measuring insert 2 and the cylindrical insert 5 but also the liquid conveying passages 1 0a, 1 Ob disposed upstream of the intake connector 9a and downstream of the outlet connector 9b, while the outer housing 9 consists of the two connectors 9a, 9b and the connecting part 9c. While the outer housing 9 takes over static functions and remains constantly flanged onto the corresponding pipe line, the inner housing 10 with the associated parts can be removed and submitted to the calibrating authority in this form for re-calibration or checking. As a result, handling during checking and re-calibration is simplified.

Fig. 5 of the drawings shows a partly sectional view, on an enlarged scale, of the measuring insert 2 according to Figs. 1 and 3. The drawing shows, connected to the fan 3, a cylindrical boss 11 which bears against an axially adjustable and lockable spindle 12.

In the case of the embodiment shown in the drawings, the adjustability and locking facility of this spindle 1 2 is achieved by means of a clamping device 1 3. Bracing of the boss 11 against the plane end face of the spindle 1 2 or against the face 1 5 on the body of the measuring insert is effected via a ball 1 4 which is connected in suitable fashion to the boss 11. As a result, a virtually friction-free mounting of the fan 3 is assured, the perfect mounting not being adversely affected even if the bearing clearance becomes comparatively great.

Claims

1. A turbine flowmeter with a measuring insert insertable into the meter casing and having a fan with a vertical axis of rotation to which the liquid is fed via a liquid guide duct located upstream of the fan, the rotary movements of the fan being transmitted to the metering mechanism of the measuring insert, the fan being enclosed by a cylindrical insert defining the liquid guide duct, inlet and outlet of the liquid being effected respectively via an intake connector and an outlet connector of the meter casing, characterised in that the cylindrically shaped insert (5) is so disposed in the meter casing (1 or 10) that it divides the stream of liquid entering the meter casing into two partial flows (A, B) partly flowing around the cylindrical insert (5), the cylindrical insert (5) being connected to the meter casing (1 or 10) by a baffle (6) which extends at an acute angle (owe) to the direction of inlet of liquid into the intake connector (1a or 9a), merging into the meter casing (1 or 10) transversely of this direction, there being disposed in the liquid conveying duct a guide device (7) having baffles (8) which extend in a radial direction and define flow ducts.

2. A turbine flowmeter according to Claim 1, characterised in that the meter casing (9, 10) has an outer housing (9) and a detachable inner housing (10) and in that the inner housing (10), in addition to the measuring insert (2) and the cylindrical insert (5) contains the liquid guide passages (10a, lOb) located upstream of the intake connector (9a) and downstream of the outlet connector (9b), while the outer housing (9) consists of these two connectors (9a, 9b) and a connecting part (9c).

3. A turbine flowmeter according to Claim 1 and 2, the fan being connected to a cylindrical boss which is braced against an axially adjustable and lockable spindle or against a face on the measuring insert body, characterised in that bracing is effected via a ball (14) connected to the boss (11) and resting against a plane end face of the spindle (12).

4. A turbine flowmeter substantially as hereinbefore described with reference to the accompanying drawings.