Emerson’s Marcelo Dultra shared a presentation, Crosby JDS: Revolutionizing PRV Applications with Diaphragm Technology, at the Emerson Exchange 2025 Conference. Here is his presentation abstract.
Dive into the benefits of Crosby JDS’s balanced diaphragm technology as an alternative to traditional bellows in pressure relief valve (PRV) applications. This session will address the limitations of bellows-style PRVs, including maintenance challenges and safety risks. Attendees will discover how Crosby JDS enhances reliability, reduces maintenance costs, and improves overall performance in backpressure applications.
The Crosby J-Series Direct Spring (JDS) Pressure Relief Valve (PRV) offers high-quality and dependable overpressure protection for air, gas, steam, vapor, liquid, and two-phase applications in a single, straightforward design.
Marcelo opened his presentation by explaining the purpose of the bellows in PRVs. They are used to negate the effects of back pressure on the PRV, which affects the setpoint at which the PRV releases overpressure conditions.
The challenge with bellows is that they have high failure rates where the bellow can rupture, causing fugitive emissions. From a safety standpoint, a failure may not open at the set pressure, and the rupture may emit hazardous or flammable gases. They are costly to maintain and may limit flow capacity, causing fugitive emissions through the bonnet vent.
Emerson has introduced an innovation to avoid the use of bellows. The balanced diaphragm technology works by having the area subjected to back pressure be the same area as the nozzle seating area, ensuring balanced operation. It is located above the guide and not in the main flow path of the media. There is no bellows spring rate effect, enhancing stability during operation.
From a performance standpoint, it enables improvements in backpressure limits and the Kb factor. This expands the application range of the spring-loaded PRV. Performance testing by Lloyd’s Register Industrial Technical Services (LRQA) includes burst tests, fire tests, and cycle tests to prove its robustness.
Marcelo explained that balanced diaphragm technology is 100x more resilient than bellows. Upgrade kits are available for Crosby J-Series PRVs. It handles 20% greater back pressure and 15% better impact of back pressure (Kb) factor than traditional bellows technology. There is no spring effect from the bellows that enhances stability.
The upgrade kit includes the diaphragm, adaptor, guide, disc holder, gaskets, and hardware. The material used in the diaphragm includes FKM, FEPM (AFLAS), EDPM, HNBR, and NBR. The material selected depends on the temperature range of the application.
Marcelo shared case studies of manufacturers and producers who have used the balanced diaphragm technology.
For one North American refiner, the challenge was increased backpressure resulting from higher throughput, and the existing PRVs were no longer sufficient to meet the required relief capacity. Replacing the 12 PRVs with JDS valves provided a 17% increase in relief capacity under the increased backpressure conditions. This solution demonstrated superior performance and scalability in this high backpressure environment.
Another case study involved an offshore oil and gas producer that implemented process changes, resulting in increased back pressure. The process media contained impurities that prevented the use of pilot-operated valves. With the Balanced Diaphragm capabilities of handling higher backpressure and having a better Kb Factor, the producer was able to match the existing orifice and face-to-face dimensions of the existing Leser valve and replace it with a JDS solution.
Marcelo summarized the comparison of balanced diaphragm and bellows technology using this table.
Follow the links above for more information on how balanced diaphragm technology can help you drive safer, more reliable, and more sustainable operations.
