I have an application where my P1=10 barg, P2=3.5 barg, max flow required is 1150 Nm3/hr of air. As I have a flow meter downstream of the regulator that requires 20D of undisturbed straight runs, just wondering if the Type 299H would be more suitable for my application, since its dual registration design has no downstream bleed if I understand the product bulletin correctly. If I understand correct, both the Type 99 and 1098 require downstream bleed with the external registration design. Is this correct?
In reply to Eric Tam:
The Type 299H has a unique registration method where downstream pressure is “dual” registered; Internally through the regulator body as well as externally through the control line tubing. The pilot does not bleed through the downstream control line, but only internally through the actuator. This dual registration method allows for higher accuracy as well as maintaining a quick speed of response and internal pilot bleed.
In reply to Jake Buford:
Hopefully you can see the attached image but the bleed only occurs through a tiny hole in the actuator between loading pressure and downstream pressure. The bleed only occurs during operation and stops during lockup. All pilot operated regulators have a downstream bleed. The 299H has an integral pilot with the bleed in the actuator. Some pilot operated regulators with external pilots bleed through a control line, but they all stop during lockup.
In reply to Garrett Winston:
Hi Garrett,
Thank you for the clarifications, the diagram and your added annotation are very clear.
This bleeding design is somewhat similar to the AFV’s design in a way that the exhaust gas is bled thorough the integral port in the main valve body and not via the control line. Is this design unique to the 299H? Cause I don’t see this internal bleed design in either the 99 or 1098.
In addition, I think the diagram you shown me is the configuration for “dual registration” with the internal port plugged, hence the exhaust gas is bled through the internal port. From the physical configuration point of view, both dual and external registration are the same externally requiring a control line, the only difference is that, with dual registration, the port between the chambers is blocked by inserting a screw (unblocked with external reg.) and the O-ring from the throat is removed (in place with external reg.). Given the advantages of dual registration, why is there still a need for “external registration” where the bleed occurs at the sensing point? Can you educate me with the advantages and disadvantages of these two configuration?
You would need external registration if you were going to use the 299H as a monitor where you wanted to sense pressure downstream of the working regulator or in any other situation where you want to register pressure at a location further downstream.
In the attached image you can see where the 99 bleed through the pilot into the actuator but then goes downstream through the control line since the throat is blocked.
I noticed this is still open for discussion.
I understand Vortex flow meter is considered to be used. Since vortex is very sensitive to turbulence, Eric wants to minimize the flow turbulence so that the stable air flow can be measured by flow meter. The bleeding flow through control line adds turbulence. From those feedback we get from other customers, the bleeding flow in control line is not high volume and will not generate big impact on the vortex meter reading.
To achieve the best performance of flow measurement, if you will not switch to other types of meter, to install the flow meter 10D after the regulator sensing port (around 500mm) can have stable flow. Please noted the control line for regulator is also proposed to have a a straight run of pipe. This arrangement depends on the footprint limitation.
In terms of the selection, I would like to mention that: type 299H for your process data will need 3/4" orifice (13.9Cv) whose max inlet pressure is 10.3barg, which is very close to 10barg. To have a higher inlet working pressure range, type 99 is a good option in terms of flow capacity and cost.
In reply to Lucy_Liu:
Hi Garrent and Lucy,
Thank you for the reply and explanation. So if my sensing point is relatively closed to the 299H, I can use dual registration, but if far away, I should use external registration, correct?
Lucy, when you say the control line for regulator is also proposed to have a straight run of pipe, are you referring to a straight run of pipe downstream of the regulator? If so, what would be the optimum straight run?
Hi Eric,
Thanks for your interest for our products and solution.
Regarding to 299H sensing option, as stated in bulletin, "External registration is used for higher capacity and/or the upstream regulator in a monitor set." and "Dual registration, with its larger orifice (control line must be piped to the primary 3/4 NPT connection on the side of the pilot), provides an improved performance as compared to internal pressure registration when used in low flow rate and high pressure drop applications." so, basically, dual or external registration is for flow capacity and accuracy benefit. And the sensing line port on man line refers to next paragraph. For your application, if the flow rate of internal registration can satisfy the required flow, you can select internal sensing, to avoid the sensing line bleeding. but unfortunately, the flow rate for internal registration 299H with 3/4" orifice is 1240Nm3/h natural gas (10.3 barg inlet and 3.4barg outlet) as shown in bulletin (around 960 Nm3/h Air, less than 1150 Nm3/h). so you will need to select from dual and external registration.
for the sensing line installation suggestion, as stated in instruction manual, "If using a control line, attach the control line from the pilot tap 2 to 3 feet / 0.61 to 0.91 meters downstream of the regulator in a straight run of pipe. If impossible to comply with this recommendation due to the pipe arrangement, it may be better to make the control line tap nearer the regulator outlet rather than downstream of a block valve. Do not make the tap near any elbow, swage or nipple which might cause turbulence. For optimal performance, use as large of a control line as practical."