When designed, installed and maintained correctly, thin plate V notch weirs provide a highly accurate solution for open channel flow measurement. In order to maintain accuracy, it’s essential that V notch weir design is calculated correctly. In this guide we’ll explain how V notch weirs work, their pros and cons, and the equations involved in V notch weir design.
What is a V notch weir?
V notch weirs really are just that – a thin plate weir with a ‘V’ notch cut into it. The weir is placed to obstruct open channel flow and allow water to flow over the notch. This enables us to accurately measure the flow, by measuring the head upstream of the V notch.
These types of weirs are particularly effective at measuring low flow rates, as the V notch weir design allows small changes in head to be accurately measured and thus the flow rate calculated.
Pros of V notch weirs
Simple design that is easy to install
Ideal for cleaner effluent, such as industrial discharge and final effluent outfall
Can be supplied as part of a compliant gauging structure
Relatively low cost to design and install
Good option for low flow rates
Can be fitted into an existing chamber, if size allows
Cons of V notch weirs
There needs to be an adequately sized weir pool and approach to sufficiently condition the flow before it reaches the weir plate to ensure accuracy in measurement
Periodic maintenance is required – it’s important that the weir crest itself is regularly checked to ensure there is no sediment or fouling. Over the longer term, no rounding or surface abrasions which can impact flow (SIRIS weir plates are manufactured using marine-grade steel to avoid this problem)
V notch weirs are not designed to work in submergence conditions and need the weir crest to be high enough to allow for free-flowing discharge
Not considered accurate for flow heads above two feet
V notch weir design: calculations
There are several standard sizes for V notch weir design. We tend to opt for 28º4′ and 53º8′ and 90º, depending on flow rate. These sizes can be calculated using the BSI equation. For higher flows we use a rectangular notch rather than a V notch.
While these are usually sufficient, because it’s essential that the sizing is correct to ensure accurate flow measurement, sometimes a non-standard size is required. There is a standard equation to calculate this, known as the Kindsvater-Shen equation.
You can read more about the Kindsvater-Shen equation and find an online calculator here.
Find out more about V notch weir design
All SIRIS thin plate weirs are fabricated from marine-grade 316 stainless steel and machined by highly-accurate laser. This ensures that they do not lose dimensional tolerance or bend/deform and won’t be susceptible to crest damage. Each weir includes a simple-to-read flow scale to provide visual validation. They are also guaranteed to meet MCERTS requirements and satisfy BS/ISO 1438, when installed and maintained by our experts.
To find out more or get a quote, call 0191 5131313 or email hello@siris.co.uk.
We’re excited to introduce the newest member of the SIRIS team, Alistair Renwick. Alistair joins us as Trainee MCERTS Inspector and will be working alongside our qualified team as he learns the ropes.
With a background in the coatings and paint manufacturing industry, Alistair is looking forward to getting stuck into his new role at a variety of customer sites under the watchful eye of our experts. His training will last for 12 months and will also include full confined space training. After completing comprehensive exams, Alistair will become a fully qualified MCERTS inspector.
As well as expanding our team of MCERTS inspectors, we’ve also invested in our other trainees. Trainee MCERTS Inspector Ethan Cook and Trainee Servicing & Installation Engineer Jordan Marley are now qualified to drive our fleet of vans, offering our customers greater flexibility and demonstrating our confidence in our young team.
Despite the unexpected challenges 2020 has thrown our way, we are excited to continue our growth as a business and provide the high level of service our customers have come to expect from SIRIS.
Effluent flow meters are designed to accurately measure the rate of flow of wastewater within a particular operating environment. Most UK businesses subject to consent to discharge permit requirements will be required to record and submit the volume and quality of the wastewater they are producing – and will require a wastewater flow meter of some description for this purpose.
There are various types of meter available, covering both open and closed channel and clean or dirty water. If the responsibility for effluent flow measurement is yours, then it is important that you understand why certain flow meters should be used in particular conditions.
This guide to types of flow meters explains the different types of effluent flow meters that are available and what to consider when both selecting and maintaining your flow measurement solution.
Types of flow meter
Effluent flow meters are typically split for suitability for either open channels or closed pipes.
Open Channel Flow Meters
Within open channel flow, the top surface of the water is usually open to the atmosphere. Examples of open flow are streams, flumes, rivers, drains and ditches. The flow can be steady or unsteady.
The flow in open channels typically occurs due to gravity, and the maximum velocity occurs a short distance below the water surface, with the HGL (Hydraulic Grade Line) coinciding with the water surface line. A cross section of an open channel will usually be triangular, rectangular, circular or trapezoidal and factors influencing flow in open channels include channel shape, fluid velocity and depth and the slope of the channel.
1. Open Channel Ultrasonic Flow Meters
Open channel ultrasonic flow meters provide a reliable and accurate method of measurement in these open conditions, used as part of an open channel flow measurement system and should be used alongside a “primary flow device” such as a flume or a weir.
The typical methodology for measuring flow in an open channel is to measure the depth of the liquid in the channel using the ultrasonic sensor while it flows through the weir or a flume, before the flow meter then uses this depth to calculate the flow rate. This method relies on the flumes or weirs being constructed and installed in a manner that ensures the water depth at the point of measurement (the gauge point) is smooth and controlled.
The ultrasonic flow meter transmits continuous high-frequency sound pulses, waiting for an “echo” to determine the exact depth of the water upstream the flume or weir.
The exact variation of formula used to then calculate the flow will differ depending on the specific primary flow device used.
Key factors:
They are simple to clean and maintain
They are very durable and long-lasting
They are accurate and reliable when installed and calibrated correctly
Easy and flexible to install and set-up
They can be impacted by certain environmental conditions such as temperature, though sun shades should be used to mitigate this
Correct specification, calibration and installation is essential to accuracy of data and success of this flow meter
2. Area Velocity Flow Meters
Area velocity flow meters calculate flow rate by understanding the cross section and nature of the channel in which it is measuring depth and velocity. There are two types of this flow meter: non-contact and wetted. The wetted version is often placed on the bed of a channel and has historically used the doppler effect to measure the velocity. Non-contact types are mounted above the channel and beam a radar (surface velocity only) or laser (surface and sub-surface velocities) to measure the velocity, with the depth often calculated using a look-down ultrasonic sensor. An area velocity flow meter for effluent water operates on the area x velocity method to calculate flow rate. This shift in frequency is used to provide a flow velocity measurement.
Key Factors:
The key rationale for use of an area velocity flow meter is the speed and convenience with which it can be installed
It is easy to install and often has no disruption to the flow
Although they reduce the initial investment needed with traditional open channel flow system measurement, their comparable accuracy and their ability to be independently verified is still debatable. Their choice should therefore be considered carefully for long-term value for money
Area velocity flow meters can offer a good short-term fix and are often used for surveys
Closed Pipe Flow Meters
Closed pipes, such as those used for the transportation of effluent flow, are able to use effluent flow meters which calculate flow by already understanding the cross section of the pipe being measured. This process is dependent on the pipe being fully flooded so that the “area” of the cross section being measured is known. Provided there is confidence in a fully developed flow profile, then the meter only needs to use sensors to measure velocity. However, the flow profile can be impacted by things such as bends, gates and twists in the pipe so it is essential that it is installed by a professional to ensure these are accounted for and the flow profile is known.
1. Electromagnetic Flow Meters
Designed for measuring liquid flow within an enclosed pipe, electromagnetic flow meters measure the voltage produced by a conductor (the wastewater) moving through a magnetic field. The voltage is proportional to the velocity of the conductor and can be converted to a flow rate. This calculation works on the principle of Faraday’s Law of electromagnetic conduction. Also commonly known as “magmeters”, they require a conducting fluid such (in this instance effluent) and a non-conducting pipe liner. These meters are popular and provide a highly accurate option for wastewater flow measurement and all SIRIS electromagnetic flow meters satisfy the necessary regulatory requirements.
Key factors:
Electromagnetic flow meters can be an ideal solution where pressure loss should be avoided as they can provide an unobstructed flow path when installed
They are a low maintenance option with no moving parts making them robust. However there should be a regular schedule of maintenance where the internal pipe bore is cleaned and inspected
Accurate installation by qualified experts is essential for their successful use
The meter must run full and be correctly earthed to the fluid to remove stray voltage
2. Clamp-On Ultrasonic Flow Meters
A clamp-on ultrasonic flow meter is a convenient method for flow measurement as they do not require the pipe to be opened up for their installation.
They work using the “transit time” theory, where the difference in transit time between those pulses going in the direction of flow, versus those going against the direction of flow is measured. This measurement of difference is then used to give the liquid average velocity along the path of the ultrasonic pulse. Using these transit times and knowing the area of the pipe it is possible to measure flow rate.
These units are also available for hire and can provide a temporary flow measurement solution.
Key factors:
There main advantage is the ease of installation, as they are attached onto the outside of the pipe
Correct installation is key to ensure there are no air gaps between the clamp and the pipe
Where cost or time of installation for an electromagnetic flow meter is prohibitive then they provide a convenient alternative
With no pressure drop or energy loss, a wide turn-down ratio and no need to cut the pipe or stop the flow, installation is easy and maintenance can be minimal
Why is correct installation and set-up essential?
Any consent to discharge permit will require correct installation, operation and maintenance of your flow measurement system.
Careful and knowledgeable selection of measurement system is important as each flow meter type varies in its suitability depending on:
The nature of the liquid to be measured
The environmental conditions
The rate and volume of flow
Whether the flow is open channel or an enclosed pipe
A pumped or gravity system
Size of pipe (for enclosed situations)
Upstream conditions to ensure confidence in either a fully developed flow profile (closed pipe) or suitable hydraulic conditions (open channel)
Downstream conditions to ensure no negative flow impact
Correct and regular calibration of any flow meter is fundamental to confirm accuracy of data. In an ideal world a flow meter would never be affected by the conditions in which it is installed, however aggressive environments and other factors can compromise their initial installation. There is also the chance that an old system may never have been installed properly in the first instance. Although no flow measurement system is 100% accurate, with all carrying some level of uncertainty, correct calibration and robust maintenance can ensure that this level is kept to a minimum.
If you are required to install a flow meter as part of your permit or consent to discharge then it is your responsibility to ensure its correct functioning and data accuracy. Failure to confirm this could lead to penalties and fines. It is always worth the investment in a professional and informed approach from an experienced MCERTS-qualified team to guarantee long-term value for money from your flow measurement system. Not only can they ensure correct set-up, inspection and calibration, but they can also provide also provide ongoing support and guidance for when things go wrong.
Get in touch with our expert team to discuss your flow measurement requirements.
There has been much chatter in the industry and wider media about the use of sewage epidemiology in the ongoing tracking of COVID-19 levels. How does this method work and how can it help in the fight against this pandemic?
Introduction to Sewage Epidemiology
Wastewater-based epidemiology (WBE) is used to measure a variety of trace substances in effluent for the purposes of public health monitoring. Indeed, the sampling of wastewater to track disease spread is not a new concept and is commonly used to measure levels of enteric viruses such as hepatitis, rotaviruses and noroviruses. Legal and illegal drug use is also monitored through traces found in local effluent sources. The SCORE network (Sewage analysis CORe group Europe) is a co-ordinated project to enable European researchers to compare the use of different illicit drugs across Europe by calculating the estimated milligrams consumed per 1000 people through analysis of their waste. You can view the results of this study in this interactive online resource.
How does Sewage Epidemiology work?
If a virus “sheds” in faeces, then theoretically it can be sampled within wastewater, typically through monitoring levels of its DNA or RNA (the genetic code of the virus). Techniques of measuring virus genetic code levels in wastewater typically fall into either quantitative polymerase chain reaction PCR (qPCR) or quantitative polymerase chain reaction PCR (qRT-PCR) approaches. Small trace amounts of DNA/RNA are amplified or elongated through highly calculated processes in order to give a reliable estimate of their equivalent real-life prevalence. For a full and detailed explanation of these scientific methods visit this page from Enzo. With SARS-CoV-2, although the RNA within faecal matter is no longer infectious, its concentration level in effluent still acts as a reliable guide to outbreak levels within the local population. With very few UK wastewater treatment works, each serving multiple cities and towns, a sample as small as a litre can give information on a vast number of people at one time.
Why is the development of Sewage Epidemiology important now?
Resistance to antibiotics, an increasing population and climate change are all contributing to an increased risk of new and mutated pathogenic organisms. Simply looking at the last two decades and the emergence of novel viruses such as SARS, MERS and Ebola shows the devastation that unrecognised viruses can bring to human existence. Being able to quickly monitor and act on the spread of these diseases is seen as critical in managing their risk to society. Intensive and costly monitoring systems such as track and trace are not always viable on a large scale due to virus infection and transmission rates. A community-level measurement method of disease levels, such as WBE, can act as an effective early warning system for infectious disease outbreaks and support more individual-level testing such as track and trace. Sampling local wastewater sources can provide comprehensive and real-time information on levels of disease in a local area, indicating when an outbreak is likely before it has even happened.
How is it being used in the fight against COVID-19?
Our current UK testing programme focuses on those already showing symptoms, meaning that asymptomatic carriers are typically not included in disease prevalence or growth estimates. With a high number of COVID-19 carriers known to be asymptomatic, the risk is that prevalence is critically underestimated when relying solely on individual testing and we could enter a second wave of exponential growth before even realising the threat.
Wastewater sampling plugs this gap through its ability to accurately gauge the threat of local or national outbreaks before they have occurred by monitoring the viral shed of both symptomatic and asymptomatic COVID-19 carriers through their faecal excretion. Typically the virus appears in faeces much earlier (3 days after infection)* than appearance of the symptoms that we are being asked to identify, such as a cough or high temperature. The sampling time can take as little 48 hours, quickly giving local authorities and government data to be able to take swift decisions in locking down or releasing specific areas.
Governments have been quick to understand and react to the potential of sewage monitoring for this critical purpose and have funded various accelerated research projects and live trials across the world. In the UK there are many trials taking place with local water authorities, government, leading universities, Defra, the Environment Agency, the Natural Environment Research Centre, the Engineering and Physical Sciences Research Council and UK Research & Innovation all partnering to progress a range of projects. A number of live trials are already taking place with local water authorities as of June 2020, with the data gathered feeding directly into the government’s COVID-19 Alert System.
Further Resources
As a supplier of wastewater sampling and flow measurement systems we have been closely following this industry development in the fight against COVID-19. Some resources that we have found particularly helpful/interesting are as follows if you would like to understand more around this topic. If you would like to speak to us about your own wastewater sampling requirements, we are continuing to provide our services during the pandemic. Please contact us for more information.
COVID-19 Regulatory Position Statement released by Environment Agency for monitoring of air and water emissions.
In a COVID-19 Regulatory Position Statement (RPS), released by the Environment Agency on 16th April, holders of installation, waste or radioactive substances activity permits have been advised that they “can make certain reasonable adjustments (such as delays or reschedules)” to environmental monitoring requirements should they be unable to comply due to COVID-19 restrictions.
Specifically the RPS states:
Written agreement must be obtained from the EA prior to making use of the COVID-19 RPS via email from your area regulatory officer or site inspector
The holder must be able to show that they have taken all reasonable steps to comply with monitoring conditions, with explanations for non-compliance
This RPS does not apply to any other activity, even if under the same legislation. Other permits or licences must be obtained for other activities.
If monitoring continues and a holder becomes aware of exceeding any limit value, they should still notify the EA immediately
You must comply with all the other requirements in your environmental permit unless they are covered by another COVID-19 RPS.
This COVID-19 RPS will be withdrawn on 30 June 2020 unless we extend it. After this date you must comply with your permit.
Monitoring Emissions to Water
With regards to monitoring emissions to water, periodic monitoring may be delayed if a permit holder:
Has staff shortages due to COVID-19
Has restricted access due to infection/risk of infection to people/places
Has restricted access to external laboratories
Guidance has been issued that the following alternatives should be considered:
Use of alternative tests e.g. (onsite chemical oxygen demand or total organic carbon measurements)
Emissions being calculated based on other parameters
If no alternative monitoring solution can be found, then the holder must contact the EA to discuss options
Samples that can not be analysed should be kept in suitable conditions for analysis at a later date
Monitoring Effluent Flow
Certification/Recertification of MCERTS for flow monitoring may be delayed but it must be rescheduled as soon as possible.
Any QM system reassessment audit should be considered for remote auditing with your assessor.
On-site maintenance of flow monitoring systems should be continued wherever possible.
All delays/reschedules should be risk-assessed for their impact to human health and the environment, which the holder must demonstrate that they are continuing to protect. For any waste operations monitoring the holder is required to not cause; a risk to water, air, soil, plants or animals; a nuisance through noise or odours; any adverse effect to the countryside or places of interest such as conservations areas and Ramsar sites.
Logging and Recording of Events
Any reasons for missing samples should be noted in the next monitoring return and all reschedules should be implemented as soon as possible – though seasonal sampling to replace missed collections does not need to be carried out. Any collected samples that can’t be analysed should be stored for later analysis where possible.
Permit holders must also maintain records for 24 months to show the reasons why the COVID-19 RPS was used. For example, records of:
staff absences
contractors being unavailable
supply chain failures
What to do if you have questions
The Environment Agency intends to monitor the use and compliance of this COVID-19 RPS through inspection and monitoring activity and are available for support and guidance.
At SIRIS we are continuing to deliver service, maintenance, inspection and installation requirements for our clients. We are able to quickly adapt our working practices to individual site social-distancing requirements, in addition to our own, in-house rigid social distancing working methodology. We are also working with clients for flexible and innovative solutions to waste flow monitoring during these challenging working conditions.
Please talk to us if you have any concerns or questions about how COVID-19 may impact your ability to comply with your effluent flow monitoring requirements.
Simon from our Sunderland Head Office took some time to explain the basics of flumes in our guide critical depth flumes and how best to maximise use of their functionality.
Using our flow measurement test rig, our instructional video guide to critical depth flumes covers:
This instructional video guide is ideal for anyone looking to enhance their knowledge and understanding of flumes. Simon is a senior member of our expert MCerts-qualified team and can help businesses and individuals with their water sampling and flow measurement requirements. Contact us if you need more detailed or tailored guidance.
The use of AV technology can cause confusion – particularly as new rules on flow to full treatment (FFT) are due to come into force. Our guide aims to help you make a more informed decision when choosing your wastewater system.
What does AV mean?
Area velocity (AV) flow meters are used for measuring flow without a flume or weir. They operate on the “area velocity principle” – a probe is inserted into the water and continuously transmits ultrasonic pulses. when particles pass through it registers the shift in area velocity and uses this to calculate the flow.
AV meters are popular because they are quick and easy to install – simply fitting them to a pipe or open-channel. They also tend to be more affordable than alternatives, such as electromagnetic flow meters.
However, a downside to AV meters is that it is difficult during MCERTS inspections to verify the accuracy of the results they are producing. This means that although they may seem like a cost-effective solutions, in reality they can often end up costing more in the long run. As MCERTS inspectors we would only recommend AV meters over other meters in certain situations, such as a temporary option or where other solutions aren’t viable.
Soon, the Environment Agency will require wastewater treatment works to comply with new regulations in the way they measure flow to full treatment (FFT). This may mean that many sites will opt for AV meters as a quick and affordable solution to meet requirements, but it is important that you make yourself aware of potential limitations before committing. In all instances you should seek the advice of MCERTS-qualified advisors.
What is Bulletin 27?
The CSA Group occasionally shares updates and additional guidance relating to the existing Environment Agency MCERTS guidelines, known as bulletins.
Bulletin 27 – “Installation and use of area-velocity flowmeters in free surface flows.” is the most recent update and provides guidance on how area velocity flow meters should be used in order to pass MCERTS inspections.
The key things it covers are:
Location and installation
Maintenance
Verification
What does Bulletin 27 mean for AV?
Bulletin 27 clarifies some areas of concern raised on how the accuracy of area velocity flow meters can be verified.
One of the key things it confirms is that there must be a “defined measurement section”. This is described as:
“a straight, stable length of channel or pipe with a constant cross section and with a length which is sufficient to create a fully developed flow profile at all expected flowrates.
Note: This will normally require at least 20 channel widths/pipe diameters upstream and 5 channel widths/pipe diameters downstream of the flowmeter.”
The additional note is important – although it acts as a recommendation it gives important guidance as to how we can accurately verify the results the area velocity flow meter provides. Bulletin 27 also explains that if these conditions can’t be met the site can still be MCERTS certified, so long as the inspector “is satisfied that that the flow measurement uncertainty conforms to the MCERTS requirements at all expected flow rates”.
Another important issue addressed is maintenance. Area velocity flow meters measure the area of the channel – and that means that any build-up of material within the channel will skew the results. It states that “the sensors and the measurement section shall be kept free from sediment and other fouling material.” In other words, the channel needs to be kept cleaned and well-maintained in order to confirm accuracy of results.
Our view
Area velocity technology should be carefully considered as a long term solution, weighing up issues of potential accuracy and verification before focusing on cost and speed of installation. Despite the relatively low initial outlay for an AV meter, inaccurate results and the issues presented by them over a long period could ultimately cost businesses and water companies more money. Electromagnetic flow meters or flumes can remove the typical issues found with AV meters and their data accuracy and, even though more costly for initial installation, can prove more cost-effective in the longer term.
It is encouraging to see further clarification on the use of AV meters from CSA Group and we believe that if these guidelines are followed – particularly the recommended installation location – then it will go some way in improving the accuracy of this technology.
Talk to the experts
To discuss your requirements, get in touch with our friendly team on 0191 5131313, or email hello@siris.co.uk.
*Confused about the role of the CSA Group? Read our guide to the key wastewater industry players.
If your consent to discharge permit requires you to monitor the makeup of your trade effluent, you will need to conduct wastewater sampling. Read on to learn what wastewater samplers are, why we use them and how they work.
What are wastewater samplers and who needs to use them?
Wastewater samplers are designed to automatically collect samples of wastewater or trade effluent at regular pre-programmed intervals.
Certain business which produce liquid waste (trade effluent) as part of their manufacturing process are required by law to have a consent to discharge permit. This is because water companies need to understand the contents and chemical makeup of any waste which discharges to its waterways to ensure it does not cause harm to people or the environment, and also that their treatment plants can handle the volume being produced.
The majority of business which produce wastewater will need a consent to discharge permit to do so, with the exception of residential homes, surgeries and clinics, grocery retailers, food outlets (e.g. restaurants), office buildings and hairdressers.
Your permit will outline conditions your business will need to adhere to, and it’s likely this will include limits for the concentration of solid particulates and organic matter and/or pH levels. In order to prove you are staying within these limits, you will need to undertake regular sampling of your trade effluent.
Inside a SIRIS refrigerated wastewater sampler unit, you will find between two and 24 sample collection bottles. The number of bottles you use will depend on your site’s individual requirements, and we will be able to help you understand the best configuration for you.
The sampler unit will be connected to your flow measurement system – we offer both vacuum and in-line options to suit above and below ground applications – and will suck wastewater in via a hose at pre-programmed intervals. A mechanical distribution arm rotates between the bottles to distribute the samples.
Data
Keeping on top of the data from your wastewater sampler is essential to make sure you’re complying with your consent to discharge permit. Wastewater systems are often situated in remote areas and are unlikely to be permanently monitored. At SIRIS, we offer a unique bespoke data monitoring system that can be installed alongside your wastewater sampler.
This is a useful tool as it can alert you to any anomalies – such as a failed sample – without the unit needing to be attended by personnel.
Talk to the experts
Our team of experts have years’ of experience in specifying and installing wastewater systems to suit individual customer needs. We encourage you to get in touch to find out how we can help with your unique requirements on hello@siris.co.uk
We hope you are well and that you and your loved ones are all keeping safe and well in these difficult and uncertain times.
We have consulted with the Environment Agency and the Government for the latest guidance on how we can best mitigate the spread of the coronavirus. We intend to adhere to these rules for as long as they are in place, not from the threat of fines, but from a deep seated belief in doing the right thing for the population.
Our team is working from home and can still be contacted via our individual email addresses. The following mailboxes will also be monitored:
Due to current restrictions we encourage you to contact us first for the latest advice regarding site visits, MCERTS inspections and installations.
We would like to reassure our key supply customers, such as food manufacturers, that any essential service work we carry out for you falls under “key worker” status as defined by the Government.
Please contact our new dedicated email address service@siris.co.uk if you require any sampler spares or emergency assistance.
Please be assured that we are fully committed to giving our customers and partners the best available service in the conditions we all find ourselves facing.
We would like to wish all our customers and suppliers well during this difficult time and look forward to resuming our full scope of work as soon as we safely can.
Effluent sampling can be an expensive requirement for businesses which are required to conduct it as part of their consent to discharge permit. Unfortunately there are a number of factors which can push this cost up further, including poor installation practice, lack of maintenance and opting for units which aren’t user-friendly. We visit sites across the UK and regularly identify issues that are costing customers money and compromising the accuracy of results. Here are our top 10 things that can go wrong with effluent sampling – and how to avoid them.
1. The sampler isn’t being correctly maintained
Unsurprisingly given the level of effluent they deal with, wastewater samplers get dirty easily and require regular cleaning. If your sampler unit isn’t being properly maintained then it can cause a whole host of issues which can result in missed samples, inaccurate results, and damage to the unit. Not only does it make the sampler unpleasant to work with, allowing parts such as the level detection pins to become dirty causes conductivity issues where they are unable to detect effluent and will continue to allow the jar to fill, resulting in overflow which can cause serious damage to the pump and internal electronics.
Our wastewater samplers are designed to be maintained easily, without the need for a technician to come out to site. Other units can be more difficult to access and clean, or large and heavy to move. Our units are compact and easy to access, making regular cleaning simple and straightforward. Read our guide to cleaning your vacuum sampler.
2. Effluent sampling parts can’t be replaced easily
When parts fail on a wastewater sampler, replacing them can be a time-consuming and complicated procedure. Our sampler units are designed to allow the easy replacement of individual parts, for example hoses which can periodically split with use, minimising downtime and costs to the business.
3. The unit isn’t user-friendly
It might sound like common sense but you’d be surprised how many effluent sampling units aren’t built in a way that is straightforward to use for both technicians and on-site operators.
Simple things like opting for a sturdy non-breakable polycarbonate vacuum chamber instead of glass, which can be easily broken if dropped instead (and they do get dropped – they’re slippery!) and having enough space to work inside the unit when wearing gloves make our units much more user-friendly and easy to work with.
4. Your effluent sampling system isn’t built to suit your needs
Every site is different and an “one size fits all” approach won’t produce the best results for your business. Our wastewater samplers allow for greater flexibility and the versatility to build a system which is fully suited to your needs. We will always spend time understanding the individual requirements of your site prior to any sale, which allows us to make tailored recommendations and set up the unit based on your bespoke specifications.
We offer both in-line and vacuum units, with bottle systems available in configurations of 2, 4, 12 and 24, depending on your requirements. The 2 and 4 options are used for daily composite sampling while 12 or 24 bottle systems tend to be used when locating process faults in the discharge.
5. There’s no refrigeration unit
Effluent contains Biological Oxygen Demand (BOD), which must be kept cold in order to be effectively measured. SIRIS samplers feature a reliable refrigeration unit with a robust thermoplastic enclosure and secure locking door to ensure it remains sealed at all times.
6. The hose is clogged
Sampling hoses can become clogged easily, preventing wastewater from being drawn into the unit. Our hoses are tapered, creating a narrower opening at the end that sits within the effluent to prevent large particles which can cause blockages from being sucked in. You’ll also find a sinker weight attached to the hose which effectively holds the hose end in the water and makes it easy to pick up and check for any blockages.
7. The distribution arm breaks easily
The distribution arm is the mechanism which rotates the sampling function between bottles. These can be flimsy, poorly constructed and break easily, stopping the arm from moving to the next bottle and disrupting the sampling process. Our units feature simple and strong mechanical arm which is much more reliable than a standard arm.
8. Effluent sampling system isn’t correctly synced with flow meter
This is typically an issue we see when the sampler has been installed by a company without an in-depth understanding of flow measurement. In order to get the most accurate results, it’s essential that your sampling system is set up in line with your flow meter and takes samples at the correct times.
9. You aren’t getting the right support from your supplier
Whens something goes wrong, you need to be sure that you have the right support to get things up and running again as quickly as possible. We’ve heard horror stories from customers who have raised sampler issues with their suppliers, only to wait up to four months for an engineer to come to site. We pride ourselves on providing a high level of care to our customers, and are always available to offer support and guidance. When we install your system, we’ll also take time to make sure you understand how to use it and keep it maintained, to avoid unnecessary issues arising later.
10. Poor installation
There are a variety of things that can go wrong when a wastewater sampler has been installed incorrectly – from using the wrong type of sampler (for example, we would never recommend using a vacuum sampler for an above-ground pipe installation), to positioning the vacuum hose too high, or not using the correct pipework. The only way to make sure that your sampler is working correctly is to get it installed by an experienced expert who has a full understanding of flow measurement and can make any necessary adjustments.
Our view on effluent sampling
The bottom line is that we are confident that you simply won’t experience any of the above issues when you opt for a SIRIS sampler and installation. Our samplers are robust, reliable and are flexible enough to be set-up in line with your requirements. Ultimately, a correctly installed system supported by a team of experts is the only way to be sure you are getting a cost-effective and reliable system.
To discuss your requirements, get in touch with our friendly team on 0191 5131313, or email hello@siris.co.uk.
