Adjusta-Cone® Technical Information
The Story of Adjusta-Cone®
Adjusta-Cone® has a huge turndown ratio compared to other DP devices. Each range has an effective turndown on 10:1 and is automatically and seamlessly changed by Adjusta-Cone® itself, meaning that whether in high range or low range, Adjusta-Cone® is always operating in its optimum setting. The combined turndown ratio of 25:1 is easily achievable (at one pressure), whilst under fluctuating pressure conditions, 250:1 can be achievable – all the while maintaining +/- 0.5% accuracy. Each meter is engineered to suit you operating conditions and using the very latest differential pressure transmitters which have multi-point calibration, this means that we will always maintain the best possible measurement uncertainty.
Every orifice plate change releases a hazardous gas cloud and this is especially dangerous with less experienced operators and/or in high H2S environments. Take those risks away completely using Adjusta-Cone®’s unique automatic adjustable ranging ability and total elimination of gas releases during the range changing process. The MVT is solidly bolted to Adjusta-Cone® using a direct mounted H style 5-way manifold. This further reduces the possibility of leak paths and optimises the process readings by eliminating impulse tubing and the additional leak paths it introduces.
Adjusta-Cone® has a unique ability to detect the flow rate and determine for itself, which range it needs to be in for any flow rate within its operating envelope. If required, human acknowledgement can be included, to prevent the range from changing too often, such as in rapidly fluctuating conditions. There is no need for human intervention to decide when to make a plate change and which size plate to install - Adjusta-Cone® does all this automatically.
The position of Adjusta-Cones range changing sleeve is detected using end stop switches. The flow computer has two sets of coefficients of discharge (v’s Reynolds Number) tables built in, one for high range and one for low range. It also has the meter’s internal bore, Cone OD and sleeve ID dimensions programmed in during set up. The customer only needs to enter the gas SG, N2 and CO2 content, or if he prefers, the full gas mole fraction data. The device can even handle a gas chromatograph input and if required can be remotely accessed using wireless technology.
By detecting the position switches, the flow computer knows which dimensions to use in the beta calculation, as well as the relevant Cd/Reynolds number values. If the sleeve is mid-travel, all flow calculations are disabled, until one or the other end stop switch is activated. The sleeve travel takes only 30 seconds to travel the entire distance, so very little miss-measurement opportunity exists, compared to the 30- minute window to replace an orifice plate. This functionality is especially important where the flow rate is changing, for example for pulsating flow, during gas-lift ramp up, or on depletion of a reservoir.
The range changing sleeve has two sets of gas tight seals, minimising potential leak paths to the environment. The sleeve is actuated using a specially designed gearbox, which even in the unlikely event of a double sleeve seal failure, can withstand full line (test) pressure (1.5 x CWP) until the opportunity to repair the seals arises. The gearbox utilises a pressure gauge to allow personnel to observe immediately if pressure exists in the gearbox, indicating a primary seal failure. Thus, personnel are doubly isolated at all times, even during range changing operations.