GB2474255A

GB2474255A - Low flow drain sampling system with automatic flow containment

Info

Publication number: GB2474255A
Application number: GB0917573A
Authority: GB
Inventors: Brian Morrie Back
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-08
Filing date: 2009-10-08
Publication date: 2011-04-13
Also published as: GB0917573D0

Abstract

A system for sampling fluids in a drainage system in low flow conditions comprising an inflatable bladder 4 for deliberately restricting the fluid flow and increasing the depth of a fluid in a pipe so as to increase the height at which sampling is possible. Preferably inflation of the bladder moves a sampling pipe or transducer 5a,5b into the fluid flow. The system preferably comprises a counterbalanced bracket 6 suspended from a pivot 2 which returns the sampling means out of the flow upon deflation of the bladder 4. Preferably, the system may signal an alarm if hazardous substances are detected, and the inflated bladder may also be used to contain the flow within the pipe. The system preferably comprises means 8 to permit sampling at programmable or remotely controllable sampling intervals, and to prevent sampling in high flow periods. The system may be retrofitted within an inspection chamber 1.

Description

Low Flow Drain Sampling System with Automatic Flow Containment Accurately and automatically sampling under low flow conditions in drains, pipes, gullies including those classified as storm water drains, surface water drains, combined sewers, overflow pipes and foul sewers is one of the biggest challenges faced by measurement scientists and normally results in the drainage system having to be modified at considerable cost to include points at which samples can be taken.

Modification also is undesirable as it increases the risk of inducing blockages and sediment can soon build up around transducers or sampling hoses/pipes.

Further, there exists a number of locations where flow is already automatically monitored where the presence of the permanent transducer or sampling pipe/tube has lead to there being a poor history of blockages and/or sedimentation build to the extent that sampling and flow has been compromised.

For these reasons at present many flows that should be sampled or monitored regularly are not and those that are often incorrectly reported. This has resulted over the years to untold damage being inflicted on the environment, biodiversity and process plant alike when harmful substances have been allowed to flow undetected and unchecked.

To overcome the aforementioned problems the present invention proposes an automatic sampling system where an inflatable pneumatic bladder with a co-located transducer or sampling pipe/hose is suspended in the drain from a special pivoting counterbalanced mounting bracket secured to the top of the inspection chamber wall.

Under automatic control, the bladder would be periodically inflated, expanding and sealing the drain plus at the same time forcing the counterbalanced bracket to pivot thus lowering the transducer towards the bottom of the channel. The sealed drain would then start to collect the flow causing the level to rise. Once the level reaches the transducers or sampling pipe/tubes the measurements would be made and the data recorded. The bladder would then be deflated and the whole assembly would swing back to the top of the drain out of the flow under the force of gravity, thanks to the counterbalance weight. Optionally, if the measurements show that the flow was hazardous the system could keep the bladder inflated to contain the flow and raise an alarm by a variety of means.

Preferably, the assembly would be fully automated such that the system would be able to record and report successful operation and on the converse malfunction.

Preferably, the assembly would be manufactured from materials such that it can withstand being deployed in areas where there are corrosive or toxic substances present.

Preferably, the system would be designed such that it could be used in potentially explosive liquid or gas environments.

Preferably, the system would be able to take a sample on demand initiated by a remote control command.

Preferably, the system would be able to cater with high flow events such as occur during storms where the bladder inflation should be inhibited.

An example of the invention will now be described by referring to the accompanying drawings: Fig 1: shows a typical drain section with its gully 2 that is accessible via a removable inspection chamber cover 1, 3. The flow in this drain 4 is for the purpose of this example too low to measure in that the depth of flow is insufficient to cover a transducer or sampling pipe/hose that would normally have to be mounted at the bottom of the gully Fig 2: shows the invention installed and in standby. The assembly comprises of an inflatable bladder 4 mounted on the end of an adjustable and counterbalanced 7 support bracket 6 to which the sampling transducer 5a or sampler vacuum tube 5b are also mounted. The bracket 6 is able to pivot about a slotted hanger bracket 2 which is mounted towards the top of the inspection chamber wall I. A slot in the mounting bracket 2 permits the whole assembly to be inserted or retracted from the surface via the inspection cover I for maintenance. The bracket 6 also carries air hoses and the vacuum tube or transducer signal cable 3 back to the control panel 8. The control panel 8 contains an air compressor to inflate the bladder, pressure regulator/transducer system to control inflation, transducer or sampler interface and microcontroller running a control programme to both run the process cycle and to the analysis the results. In addition the control panel 8 would have the facility for an alarm sounder and a connection to an external remote telemetry device that could send messages using low power radio, PMR radio, Satellite uplink, PSTN modem, GSM call or SMS text.

Fig 3: shows the invention with the bladder inflated sealing the drain whereby the inflation of the bladder S has caused the bracket to pivot lowering the transducer 5a or sampling pipe/tube 5b into position ready to sample the flow.

Fig 4: shows the invention with bladder 4 inflated and where the flow has built up to the point where the depth is now sufficient for sampling to take place. Once the sample has been successfully taken, analysed and stored the bladder 4 is deflated and the assembly returns to the stowage position out the way of the flow. However, if the sample shows that a hazardous substance has detected the system can optionally maintain the inflation of the bladder 4 to contain the flow and the control panel can raise an alarm either audibly via the sounder or remotely via the telemetry link.

The whole sampling cycle would operate continuously as programmed andlor could be initiated or interrupted by an external command. 4 3

Claims

Claims 1. A system that can be fitted within a drainage system to permit sampling of the flow to take place in low flow conditions, by deliberately restricting the flow using an inflatable bladder to creates and obstruction such that the depth of the substance in the pipe to increase to the point where sampling is then possible.
2. A system that can be fitted within a drainage system to permit sampling as per claim 1, that can be retrofitted via the inspection chamber by means of a counterbalanced adjustable bracket system suspended from a pivot.
3. A system that can be fitted within a drainage system to permit sampling as per claim 1, which by force created by the inflation of the bladder actively moves a co-located transducer into and out of the flow.
4. A system that can be fitted within a drainage system to permit sampling as per claim 1, whereby use of a counterweighted bracket assembly returns the transducer or sampling pipe/tube out of the flow to minimise the risk of blockages, sediment build up and corrosion.
5. A system that can be fitted within a drainage system to permit sampling as per claim 1, which can proactively contain the flow by maintaining its inflated state whenever hazardous substances are detected.
6. A system that can be fitted within a drainage system to permit sampling as per claim 1, which can proactively generate an alarm whenever hazardous substances are detected.
7. A system that can be fitted within a drainage system to permit sampling as per claim 1, that permits sampling of the flow to take place in low flow conditions at programmable or remotely controllable sampling intervals.
8. A system that can be fitted within a drainage system to permit sampling as per claim 1, that permits sampling of the flow to take place in low flow conditions but has the intelligence to know that a high flow condition exists and to not obstruct the flow during this period.