Hawk - Gas and Liquid Flow Measurement
Gas Flow
The Hawk can monitor gas flow via an orifice plate ( AGA3-90 or ISO5167 ), or a gas turbine (AGA7). All gas flows are compensated for deviation from the ideal gas law , compresability or the Z factor, either using AGA8-90 or Redlich-Kwong with Wichert-Aziz Sour Gas equation of state.
An Orifice Plate meter run can be monitored with a Hawk equuiped with differential pressure sensor, static pressure sensor and external temperaure probe. With these threee sensors the Hawk 9000 can calculate the gas flow real-time, log the data and displays the gas flow rates on the built in LCD display.
The Hawk 9000 can be used to measure gas flow using a optional orifice testing kit and a user supplied meter run
One of the draw backs when using a orifice plate is the plate has to be changed when the gas rates goes outside the orifice plates calibrated flow range. For operator convenience the Hawk comes with three ways to change the plate size. If you are using a real-time connection it can be changed on the fly when monitoring your sensors using CalWin. You can also download into the Hawk new orifice plate settings using a laptop with a USB/Serial Interface box or programmed via a SD card inserted in the front. What you will find however that operator wont be changing the plate quite as often as the Yokogawa differential meter can measure a much wider span than a paper chart recorder.
Gas turbines have several advantages over orifice plate flow measuring systems. With a much larger turndown ratio, which is the ratio of the maximum flow to minimum flow, a gas turbine is capable of measuring a much wider variation in flow rate without adjustment.
Up to three turbines can be interfaced to the Hawk at the same time. Supprted are bi-directional as well as positive displacement meters
Typically depending on the turbine the ratio is 40:1 to 100:1, where as a orifice plate system is 5:1. Another advantage is the low back pressure. In the gas turbines construction there isn't much of a flow restriction, so any differential pressure created is much lower. This helps prevent liquids dropping out of the flow stream for wet gas measurement.
As a result for measuring low gas flows or for widely varying flows such as Coal Bed Methane, Plunger Lift, Wet Gas, and Fuel Gas a gas turbine meter is much more effective than a orifice plate.
Liquid Flow
In addition to gas the Hawk can monitor up to three liquids flows via its high performance turbine card that comes with several advanced features
Pulse Filtering: Each input is monitored for frequency pulse by pulse. This allows the user to filter out gas packets that can sometimes get into liquid flow lines, giving large false readings.
Bi-Directional Capable: If your application requires monitoring gas or liquid in two directions in the same flow stream the Hawk allows up to two bi-directional turbines to be monitored at the same time.
Open Collector or VRS pickup: Software set-able to use either the standard non-powered VRS turbine or a open-collector pickup often used on powered pickups.
Large Frequency Range : Each turbine input is capable of measuring frequencies up to 5000 Hz at 300 mVpp and for frequencies lower than 1000Hz the minimum voltage is 20 mVpp.
