The TP-1 Transient Pressure Monitoring System
In 2004, Pipetech International introduced the TP-1 Transient Pressure Monitoring System, a digital system that overcomes several of the limitations of previous digital systems. The TP-1 is capable of monitoring over extended period of time in a “snoozing” mode, recording background pressure at a user-set interval between once per second and once per day. Although the system appears to be snoozing, in reality it is very busy. It continuously samples the pressure 1000 times per second and computes a running average. Effectively the system algorithm has a built-in alarm clock that goes off when a pressure is detected that differs significantly from the average – in other words when a transient is detected. When this occurs, the system “wakes up” and records all data at another user-set rate up to 100 Hz. This continues until the transient has passed, at which time the system goes back to the “snoozing” mode. The scheme is shown graphically in the figure .
The so-called TP-1 Transient Pressure Monitoring System is comprised of the following components:
|TP1 Controller||The Controller processes all of the input signals, and performs all of the logic in the system. It also stores all of the historical data until it is retrieved by the user.|
|Pressure Transducer||A dynamic pressure transducer capable of recording both positive and negative pressures with a frequency response of not less than 1 kHz is required. For petroleum applications, it must be certified for operation in explosive environments.|
|Communications||The user will communicate to place the system in operation, adjust the user-set parameters, and upload pressure data. The TP-1 allows three different communication links: a wired LAN link, or a standard wireless system such as the Personal Digital Assistant (PDA) with wifi capability, or a broadband cell/internet link.|
|Data Analysis Tool||The TP-1 data is stored in tabular form in a standard database, however the data review is greatly facilitated by software that allows graphical displays meeting the user’s needs, as will be shown in the following section.|
The TP-1 has been extensively tested under laboratory and field conditions. Early applications included water pipelines, wastewater pipelines, fire suppression systems, water treatment plants and industrial process applications. The unique capability of the TP-1 to capture waterhammer events in great detail is shown in Figure.
This graph depicts a period of six seconds during which a pump shutdown occurred, resulting in a waterhammer transient. The positive phase of this event has a duration of 0.05 seconds, illustrating the difficulty of capturing such an event with a data logger recording at 20 Hz.