TotalFlow uFLO, User Manual, Page: 105 / 132

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Term Definition
Decibel A logarithmic measure of the ratio of two signal levels. A practical unit of
gain.
Default A value assigned or an action taken automatically unless another is
specified.
Delivery Point Point at which gas leaves a transporter's system completing a sale or
transportation service transaction between the pipeline company and a
sale or transportation service customer.
Demand Day That 24-hour period specified by a supplier-user contract for purposes of
determining the purchaser's daily quantity of gas used (e.g., 8 AM to 8 AM,
etc.). This term is primarily used in pipeline-distribution company
agreements. It is similar to, and usually coincides with, the distribution
company "contract day”.
Demand Load The rate of flow of gas required by a consumer or a group of consumers,
often an average over a specified short time interval (cf/hr or Mcf/hr).
Demand is the cause; load is the effect.
Demand Meters A device which indicates or records the instantaneous, maximum or
integrated (over a specified period) demand.
Demand, Average The demand on a system or any of its parts over an interval of time,
determined by dividing the total volume in therms by the number of units of
time in the interval.
Diaphragm A bellows inside a displacement type gas meter. Also, a membrane
separating two different pressure areas within a control valve or regulator.
Differential Pressure The pressure difference between two points in a system. For example, the
difference in pressure between the upstream and downstream taps of an
orifice plate, used to measure volume passing through the orifice.
Digital A signal which has distinct states, either on or off (0 or 1). Digital
computers process data as binary information having either true of false
states.
Digital Data Information transmitted in a coded form (from a computer), represented by
discrete signal elements.
Digital Data Exchange
or Dynamic Data
Exchange A Microsoft data exchange format generally used to transfer data from one
program to another. It is a very simple format to use and Totalflow
customers often use TDS to acquire data from Totalflow devices and then
transfer the data to an Excel spreadsheet using DDE. The Totalflow
Driver, TDS32, supports DDE and its network version, NetDDE.
Digital Electronics The branch of electronics dealing with information in binary form.
Digital Input Refers to the signal received in binary format.
Digital Output Refers to the signal emitted in binary format.
Digital to Analog
Conversion The process of translating discrete data into a continuously varying signal.
Common uses are to present the output of a digital computer as a graphic
display or as a test stimulus.