Assentech for a new breather valve
Most operators come to Assentech for a new breather valve. Fewer realise that Assentech supports the full lifecycle of that valve. On an anaerobic digester, the stages between purchase, installation, inspection and maintenance are where compliance, safety, emissions control and gas recovery are either protected or compromised.
Across the biogas and water sectors, there is often an assumption that every breather valve arrives from the manufacturer fully tested, correctly assembled and set, ready to protect the tank or digester. It is a comfortable assumption. In most cases, it is wrong.
We have arrived on site to service valves and found original packaging still sealed inside them. Components that were never going to seal correctly, sitting on live digesters. The valve looks fine from the gantry. The paperwork to prove it works does not exist.
PVRVs, also known as breather valves, are critical pressure relief devices on anaerobic digesters. They are the last line of protection against over/under pressure during normal operation. However, they are also recognised as one of the largest sources of biogas emissions, a concern acknowledged in the Government’s Methane Reduction Plan and now increasingly scrutinised through the Environment Agency’s Appropriate Measures for permitting.
A valve that vents early, fails to reseat, sticks, leaks or does not open at the required setting can quickly become a safety, environmental and compliance issue. Without verified leak rate data, operators cannot confidently demonstrate that the valve is protecting the asset, controlling emissions or performing to the required standard.
The Biogas Problem Nobody Likes To Admit
Anaerobic digestion creates its own valve challenges. Foam formation due to pH imbalances can block and contaminate the valve over time. Left unchecked, it can restrict or block the vent path entirely, leaving the next pressure event with nowhere to relieve safely.
Combined with poor valve design, missed maintenance, unsuitable materials, painted seats or lack of verified testing, the device intended to protect the tank can become one of its weakest points.
Reducing fugitive emissions from leaking valves improves safety for staff and neighbouring communities, protects valuable gas assets and supports operational profitability. Fixing a leaking valve delivers environmental, safety and commercial benefits at the same time.
The Standard, And Where It Falls Short
Biogas facilities are increasingly being recategorised under COMAH regulations, placing greater emphasis on the registration, inspection and maintenance of critical safety assets. For breather valves, the recognised standard governing design, construction, testing and marking is API 2000, also co-branded as ISO 28300.
API 2000 has existed since the 1960s and was originally developed to ensure breather valves were correctly designed, assembled, tested and fit for installation on tanks and digesters. However, the standard was written long before methane emissions became central to operational, environmental and regulatory frameworks.
This is where modern testing must go further. It is no longer enough to assume that a valve opens and closes. Operators need evidence that the valve is set correctly, seals effectively, relieves safely and provides defensible leak rate data when challenged by regulators, insurers or internal compliance teams.
Raising The Standard In The Field
Assentech is dedicated to raising standards in the safety, reliability and environmental performance of low-pressure relief devices. As one of the first companies to test customers’ breather valves in the field to API 2000, Assentech has since developed and supplied Vent-Less test benches internationally.
Vent-Less testing goes beyond basic functionality checks by measuring leak rate, supporting emissions assessment and helping operators understand real valve performance. While the standard functionality test is typically carried out at 75% of set point, real operating conditions can bring a valve closer to its opening pressure or vacuum setting. For this reason, Vent-Less volume leak tests can also be conducted at 90% of set point, providing a more representative view of in-service performance and potential product, gas or vapour loss.
Vent-Less is an award winning, fully automatic and rapid testing technology with self-calibrating capability and advanced data transfer. It generates complete API 2000 compliant test certificates within 30 seconds of test completion. Certificates are securely accessible online, enabling operators to review year on year performance, identify valves approaching the end of their serviceable life and plan maintenance, replacement and budget forecasting. The patented Vent-Less bench range now extends to six models.
Full Lifecycle, One Partner
Assentech continues to build a growing community of trained and responsible valve testing technicians, improving access to reliable leak rate and performance data across the industry.
Alongside this, the company provides full lifecycle support for breather valves, including specification, commissioning, installation support, inspection, testing, reset, servicing and tailored maintenance programmes. The objective is to equip operators with the knowledge and evidence needed to make better decisions, improve asset performance and challenge inferior products or poor practice.
Assentech also provides a free to use Emissions Calculator accessible on the homepage of our website to convert emissions volumes into cost impacts and global warming potential.
Operators do not have to commit to a full lifecycle programme from the outset. Assentech can support the stage where the risk is greatest, whether that is before purchase, before installation, during inspection, after service or for regulatory scrutiny.
The key is not simply to repair the valve when it fails. It is to understand whether the valve was suitable, correctly tested, installed, maintained and still capable of protecting the asset throughout its serviceable life.
The Numbers Worth Pausing On
Assentech estimates that a significant proportion of breather valve service companies do not have sufficient understanding of API 2000, or the correct equipment to test fully to the standard. As a result, many customers are unaware of testing limitations and may lack the technical knowledge needed to scrutinise certification at purchase, installation or service.
We estimate there are approximately 40,000 breather valves in the UK, yet only around 1,000 are currently tested in accordance with API 2000. No operator would knowingly install a valve that does not meet the required standard. That is why clear evidence must be demanded, and why manufacturers, suppliers and service providers must prove performance, not simply state compliance.
Aerial view of the tanks of a UK sewage and water treatment plant enabling the discharge and re-use of waste water and re-use of waste water
