GB2578461A

GB2578461A - Flushing rig

Info

Publication number: GB2578461A
Application number: GB1817603.2A
Authority: GB
Inventors: Barry Robinson Peter; Gary Crick Stephen
Original assignee: Dosafil Ltd
Current assignee: Dosafil Ltd
Priority date: 2018-10-29
Filing date: 2018-10-29
Publication date: 2020-05-13
Also published as: GB201817603D0; WO2020089575A1

Abstract

The invention concerns a flushing rig 10 for use in flushing a pipework system such as a heating or cooling system. The flushing rig 10 comprises an inlet port 12 connectable to the pipework to be flushed, an outlet port 36 connectable to the pipework to be flushed, a pump 16 configured to propel water from the inlet port 12 to the outlet port 36, a filter vessel 24a, 24b connectable via a valve arrangement 22a, 22b, 32a, 32b between the inlet port 12 and the outlet port 36, the filter vessel containing a filter (42, fig 4) for filtering water passing through the filter vessel (42, fig 4) and a bypass passage 26 incorporating a bypass valve 28, so that when the bypass valve 28 is open water is able to flow from the inlet port 12 to the outlet port 36 without passing through the filter vessel (42, fig 4). A sensor arrangement (60, 62 fig 2) for detecting when the filter 24a, 24b is clogged or blocked may be present and for opening the bypass valve 28 in response.

Description

FLUSHING RIG

The present invention relates to flushing of pipework, and particularly to a rig for use in that context.

Pipework systems in buildings, in particular heating and cooling systems, need to be cleaned before they are commissioned and put into service. The cleaning process involves flushing the pipework to remove foreign matter, which can include mill scale, jointing compound and a variety of building debris. Such contaminants may, if allowed to remain, cause blockages for example in strainers, valves and narrow pipework such as in heat exchangers. They may also promote corrosion and encourage microbial proliferation.

To ensure removal of the foreign matter, and to comply with regulations, each part of the pipework needs to be subject to flow of a certain velocity, over a predetermined period, to reliably mobilise the and so remove the particulates. This flow needs to be continuous. If there is a pause in flow then the foreign matter may settle.

In large building projects, the cleaning process often involves use of a pump installation provided in the building's basement and connected to a main riser of the pipework. The pumps used may be a permanent part of the heating or cooling system, or may be a temporary installation to be removed once the system has been flushed. Using valves built into the pipework, flow from the pump installation is fed to selected portions of the pipework in turn, in an attempt to ensure that each part of the pipework receives the required rate and duration of flow. Water used for flushing is often exhausted to the drain, without being recirculated. The process can be complex. In a large building, with a large volume of individual pipes to be flushed, the process can consume thousands of man hours.

The conventional pre-commission cleaning process is problematic. One important problem in practice is that it relies on much or all of the heating or cooling system being complete. Hence it may not be possible to commence flushing and then commissioning the system until the pipework has been completed and the building itself is nearing completion. But construction time commonly over-runs on major building projects and delays in handing over the building may be expensive. The flushing process -being reliant on flow from a shared pumping installation -is inherently sequential and time consuming, and has the potential to delay handover.

Flushing large volumes of water to drain is in itself undesirable environmentally. For that reason, and where water conservation is an issue, it may be unacceptable to authorities such as utility companies. The volume required is typically several times the total volume of the pipework system. Conditioning chemicals are added to the water used for flushing and it is not desirable to put those into the ecosystem.

A different approach is therefore desirable which can help to ensure that this process does not delay commissioning of the building and to overcome the other shortcomings of the conventional technique.

GB 2478532 and U52013/0319464, both in the name of Barrett, describe an apparatus for cleaning heat exchanger pipework, having a pipework conditioning apparatus which receives a proportion of the water circulating in a closed-loop pipework system and removes particulate contaminants from that water, which is returned to the pipework system. The apparatus also comprises a water conditioning apparatus which conditions the water prior to its delivery into the pipework by removing particulate contaminants and killing microorganisms. The apparatus is said to be suitable for use in cleaning of pipework prior to commissioning and in periodic cleaning during the lifetime of the pipework. The filling and cleaning apparatus described in these cases avoids the need to flush cleaning water to drain but does not address the problem of the time taken to carry out the cleaning process.

According to a first aspect of the present invention, there is a flushing rig for use in flushing a pipework system, the flushing rig comprising: an inlet port connectable to the pipework to be flushed; an outlet port connectable to the pipework to be flushed; a pump configured to propel water from the inlet port to the outlet port; a filter vessel connectable via a valve arrangement between the inlet port and the outlet port, the filter vessel containing a filter for filtering water passing through the filter vessel; and a bypass passage incorporating a bypass valve, so that when the bypass valve is open water is able to flow from the inlet port to the outlet port without passing through the filter vessel.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-Figure 1 is a schematic representation of a pipework flushing rig embodying the present invention; Figure 2 is a front view of the same pipework flushing rig; Figure 3 is a side view of the pipework flushing rig; Figure 4 is a section through a filter vessel of the pipework flushing rig; and Figure 5 is an exploded view of a lid of the filter vessel.

The pipework flushing rig 10 described herein enables the pipework of a heating or cooling system to be flushed zonally. A certain zone of the system can, using the flushing rig 10, be flushed and so prepared for commissioning separately from other parts of the system and even before other parts of the system have been completed. To this end the flushing rig 10 according to the present embodiment has a weight and bulk small enough to enable it to be moved from one place to another within a building, and is configured to be essentially self-contained, so that it can easily be taken to the intended point of use within the building and then -following connection to the pipework -can be quickly put to work flushing the pipework. The conventional approach relies on water supplied through the building's main riser, and can thus only be implemented once the pipework is complete or at least close to completion. But the zonal flushing made possible by the present invention can instead be commenced much earlier in the building's construction. As an example (and without limitation), it could be that pipework is installed floor-by-floor in a building. As pipework on one floor is completed, the flushing rig 10 is installed on that floor and connected to the pipework on that floor, which is then flushed. This can be done while other building work proceeds. Each floor can thus be completed and flushed in turn. In this scenario the bulk of the pipework will have been flushed and so prepared for commissioning by the time the heating or cooling system as a whole has been completed. In this way, flushing of the pipework is removed from the critical path to handover of the building, which is a major commercial benefit.

The flushing rig 10 serves to circulate water through the chosen zone of the pipework in closed loop fashion whilst filtering particulates from it, avoiding the need for multiple system volumes of water to be exhausted to drain. Its filter(s) collect material and so clog over time, but the rig 10 provides for detection of filter clogging and provision is made for the filter elements to be removed and replaced without suspending circulation of water (and the consequent need to begin the process afresh). Filter replacement may allow air to enter the system but provision is made for the water to be automatically de-aerated as it passes through the flushing rig 10.

The flushing rig 10 has a rig inlet port 12 connectable to the chosen point in the pipework and leading via a suction diffuser 14 to a pump 16. The suction diffuser 14 serves, in a manner familiar to the skilled person, to condition flow into the pump 16 and so improve its performance. The suction diffuser 14 may contain vanes which reduce turbulence in the water flow. From the pump 16, water is supplied to an upstream manifold 18 from which emerge: (a) a first filter input line 20a leading via a first filter inlet valve 22a to a first filter vessel 24a; (b) a second filter input line 20b leading via a second filter inlet valve 22b to a second filter vessel 24b; and (c) a bypass line 26 incorporating a bypass valve 28.

First and second filter output lines 30a, 30b incorporate respective filter output valves 32a, 32b and lead respectively from the first and second filter vessels 24a, 24b via; (a) a downstream manifold 25 in which they converge and meet bypass line 26 (downstream of the bypass valve 28) and (b) a flow meter 34 to a rig outlet port 36 connectable to the building pipework.

Details of the filter vessels 24 are best seen in Figure 4. In this particular embodiment water is input laterally into a neck portion 38 of the vessel through the input line 20 and flows downwardly through the filter vessel 24, passing through a bubble coalescing device 40 and a bag type filter 42 to reach the output line 30.

The function of the bubble coalescing device 40, which in the present embodiment is more specifically a micro-bubble coalescing device, is to cause small air bubbles in the flow to coalesce to form larger bubbles which will rise to an automatic air vent 44. In this way the filter vessel 24 causes the water to be de-aerated. In the present embodiment the bubble coalescing device comprises a ring structure which offers large openings for flow of fluid, but also has a large surface area for collection of bubbles. Suitable ring-shaped metal or plastics structures are sold under the generic name "Pall rings". Suitable automatic air vents 44, able to release air without problematic loss of system pressure, are in themselves well known in the art.

The filter vessel 24 has at its upper end an opening which is not seen in Figure 4 as it is closed by a removable lid 46. The vessel's opening is large enough to enable the filter 42 to be inserted and removed through it. The lid 46 is able to be disengaged from the filter vessel 24 by turning it, and is thus removable from the filter vessel 24 to leave its upper end open. The dosing vessel 24 will typically be isolated from the fluid flow before the lid 46 is removed, but in the event of misuse there is the possibility that the lid might be released while the filter vessel 24 is exposed to elevated pressure in the system. As a safety feature, the lid 46 engages with the neck portion 38 of the filter vessel 24 in such a manner that its disengagement involves first moving it to a captive pressure release configuration, in which a path is opened for release of pressure but the lid 46 remains captively attached to the neck portion 38 and so cannot be ejected, and then moving the lid 46 to a full release configuration in which it is able to be removed from the filter vessel 24. If, upon moving the lid to the captive pressure release configuration, the user observes that gas or liquid is being expelled, then the user is able to close the lid 46 and so prevent mishap.

The lid 46 is seen in Figure 5 to be formed of two parts -a securing ring 50 and a captive cover 52. A threaded collar 54 is received in and secured to the open upper end of the filter vessel 24. In the present embodiment the collar 54 is welded to the filter vessel 24. It carries an external screw thread 58 to engage a complementary internal thread (not seen) of the securing ring 50. The cover 52 has a circumferential shoulder 56 which engages with a complementary shoulder (not seen) inside the securing ring 50 to render the cover captive. When the securing ring is 50 screwed down onto the collar 54, the cover 52 is sandwiched between the securing ring 50 and the collar 54 and a seal is formed. Loosening the securing ring 50 allows this seal to be broken and pressure to be vented, but the cover 52 remains captive until the securing ring 50 has been screwed fully off the collar 54.

In normal use of the flushing rig 10, during flushing, the bypass valve 28 is closed, blocking flow through the bypass line 26, and the filter inlet and outlet valves 22a, 22b, 32a, 32b are open, so that water flow driven through the apparatus by the pump 16 is split between the two filter vessels 24a, 24b, being thereby filtered to remove particulates before being exhausted from the rig back into the pipework via the rig outlet port 36.

In order to detect when filters 42 are clogged, the flushing rig is configured to detect a pressure drop across the filters 42. For this purpose it has an upstream pressure transducer 60, which in the present embodiment detects pressure in the upstream manifold 18, and a downstream pressure transducer 62, which in the present embodiment detects pressure in the downstream manifold 25. Output signals of the pressure transducers 60, 62 are fed to an electronic controller 64 which, by subtracting one from the other, obtains a value for the filter pressure drop. The pressure drop may be displayed to an operator. This may be by means of a display on the electronic controller 64. Additionally or alternatively the flushing rig 10 may output this and other operating information through a suitable digital network. This may be done using the SMS (texting) system, via email, through the building's own management system, or in any other suitable manner.

In the present embodiment the bypass valve 28 is electrically controlled by the controller 64. When the pressure drop reaches a threshold value (indicative of a need to clean or replace the filters 42) the controller 64 opens the bypass valve 28, enabling the water to bypass the filters 42. A signal is given to the operator to alert them to the need for action. Circulation of water continues at the required velocity so that settlement of solids from the water is prevented. Filtering of the water is temporarily suspended but this is not problematic. Bypassing the filters 42 in this way prevents damage to the filter media, pump or other components and enables filter replacement without suspending circulation of the water.

To replace the filters 42, the operator closes the filter inlet and outlet valves 22a, 22b, 32a, 32b to isolate the filter vessels 42 from the water flow. The lid 46 of one of the filter vessels 42 can then be removed, enabling removal and replacement of the filter 42. Filters 42 may be replaced with a different item or may be washed and returned to service. Often the flushing process entails use of successively finer filters, so that coarse particulates are removed first and then smaller ones. Once a clean filter is in position, the lid 46 can be replaced and the corresponding filter inlet and outlet valves 22a, 22b, 32a, 32b opened, followed by closure of the bypass valve 28.

The pump 16 of the present embodiment has a variable speed drive ("VSD") controlled by the controller 64, which receives the output signal of the flow meter 34, to provide a chosen rate of flow, and hence a corresponding flow velocity through the pipework being flushed.

The flushing rig 10 may be mounted on castors or skids to enable it to be moved within a building. To function it needs to be connected to the building pipework and to a source of electrical power, but it is otherwise an essentially self-contained unit easy to install and remove. While it is not intended to limit the scope of the present invention by reference to any particular dimensions, the flushing rig 10 of the present embodiment has a footprint approximately one metre square, enabling it to pass through conventionally sized doorways and to be moved from floor to floor in lifts.

For cases where a single flushing rig 10 is unable to provide sufficient water flow, two or more similarly formed rigs 10 may be manifolded, their inputs and their outputs being connected together so that total flow is cumulative. In this way even large systems may be zonally flushed using rigs that are easily able to be moved about the building as needed.

In some cases water treatment chemicals may need to be introduced to the pipework. This can easily be achieved using the present embodiment by removing the lid 46 and introducing the chemicals, in solid or liquid form, directly into the filter vessel 42.

It should be noted that where references are made herein to "pipework", this is intended to encompass all the internal parts of the relevant system, and includes for example heat exchangers, which may for example be in the form of radiators, as well as valves etc.

Claims

CLAIMS1. A flushing rig for use in flushing a pipework system, the flushing rig comprising: an inlet port connectable to the pipework to be flushed; an outlet port connectable to the pipework to be flushed; a pump configured to propel water from the inlet port to the outlet port; a filter vessel connectable via a valve arrangement between the inlet port and the outlet port, the filter vessel containing a filter for filtering water passing through the filter vessel; and a bypass passage incorporating a bypass valve, so that when the bypass valve is open water is able to flow from the inlet port to the outlet port without passing through the filter vessel.
2. A flushing rig as claimed in claim 1 in which the valve arrangement is configured to selectively isolate the filter vessel from water flow through the flushing rig.
3. A flushing rig as claimed in claim 2 in which the filter vessel has an opening through which the filter is able to be inserted and removed, the opening being closable by means of a lid, so that by opening the bypass valve, isolating the filter vessel from the water flow and opening the lid, the filter vessel is able to be removed without suspending water flow.
4. A flushing rig as claimed in any preceding claim further comprising a sensor arrangement for detecting when the filter is clogged and for opening the bypass valve in response.
5. A flushing rig as claimed in claim 4 in which the sensor arrangement comprises respective pressure sensors upstream and downstream of the filter through which a pressure drop across the filter is able to be determined.
6. A flushing rig as claimed in claim 5 in which the bypass valve is electrically controlled, the flushing rig further comprising an electronic controller configured to receive outputs from the pressure sensors and to open the bypass valve when the pressure drop exceeds a threshold.
7. A flushing rig as claimed in claim 6 in which the electronic controller is configured to output a message to an operator when the pressure drop exceeds the threshold.
8. A flushing rig as claimed in any of claims 5 to 7 in which the lid is configured to be disengaged by a process which involves first disengaging the lid by moving it to a captive pressure release configuration, in which a path is opened for release of pressure from the dosing chamber but the lid remains captively attached and so cannot be ejected, and then moving the lid to a full release configuration in which it is able to be removed from the dosing vessel.
9. A flushing rig as claimed in any preceding claim further comprising an automatic air vent for de-aerating the water.
10. A flushing rig as claimed in claim 9 in which the automatic air vent is provided with a bubble coalescing device.
11. A flushing rig as claimed in any preceding claim which is a self-contained unit configured to be carried, trundled or slid from one place in a building to another.
12. A flushing rig as claimed in any preceding claim comprising a pair of filter vessels each connectable via a respective valve arrangement between the inlet port and the outlet port.