The Reference section of AirTalk.com provides key information about our hardware and software products, cable pressurization design concepts, leak locating strategies and a variety of other information. Visit this section often to learn more about cable pressurization and what we have to offer.
Leak Locating Worksheets
The best approach to leak locating in a cable pressurization system is to use a logical and organized step-by-step procedure. When a defined leak locating strategy is applied, the most damaging leaks in the system are identified first. These are the ones that generally bring down route delivery pressures and reduce cable protection throughout the system. Only after these major leaks have been located should the emphasis shift to the smaller leaks.
To provide a structure for the leak locating process, System Studies has developed seven leak locating worksheets, each of which addresses a specific leak locating challenge. The links on the left generate information about the selected worksheet and explain how it can be used to organize information and assist in the leak locating process. In order for a worksheet to be beneficial both as a leak locating instrument and as a record keeping source, it must be used as intended. All of the procedures outlined on the back of each worksheet need to be performed conscientiously. Precise pressure and flow readings must be taken and recorded in the appropriate places on the form. And, finally, all Air Flow Calculations, Zero Leak Projections, and Back Projections must be accurate.
You'll notice when you access a specific worksheet that a hyperlink is provided below the worksheet illustration. This link generates a PDF version of the form that can be printed and used in the field. If you don't have Adobe Acrobat® Reader™ installed on your system, you can download it for FREE directly from
Adobe.
Worksheet A—Reading Flows at Manifold and Meter Panels
This worksheet is used to record pressure and flow readings at air pipe manifolds and meter panels. It will help to identify problems in the air pipe and indicate the highest flowing cables on each air pipe run. When reading flows on a distribution panel in the central office, a separate worksheet can be used for each panel. This will enable you to make future comparisons of flow changes. Another option would be to record all distribution panel flows on the same worksheet. This would make it easy to prioritize the highest flowing panels. With either method, you should always set priorities to repair the highest flowing, most damaging leak first.
In a pipe system Worksheet A is used to set leak locating priorities as well as to identify potential pipe problems. Once the flows at all manifolds on an air pipe have been recorded and totaled, they should be compared with the total flow at the pipe alarm panel. If the sum of the manifold flows is not within 70 percent of the total pipe flow, the air pipe should be purified to locate such potential hazards as pipe leaks, buffer hoses not removed after splicing (commonly referred to as "cheater" hoses), unrecorded manifolds ("ghost" manifolds), or mislabeled and transposed air pipes.
Worksheet B—Chasing Air Flow at a Manifold
Worksheet B is used in dual feed air pipe systems when dispatch priorities point to a particular air pipe manifold that shows a high flow condition. It outlines a step-by-step procedure to locate the cause of the high manifold flow. It also serves as a record keeping device for future review, questions or similar problems at the same location. Side one of Worksheet B consists of 15 boxes, each of which represents a unique utility hole or pressure reading location. These boxes are used to record:
- Delivery pressure, air flow, and cable pneumatic resistance
- Calculated Zero Leak Projections (area of search), Air Flow Calculations
- Utility hole numbers, locations, and the distances between them
- Cable structure (splice closures and interlacing)
- Individual cable pressures
Worksheet C—Leak Locating in Cables Leaving the Central Office
Cables leaving the central office can be systematically checked for leaks by following the procedures outlined by Worksheet C. When PressureMAP's Dispatch Priorities indicates that the distribution panel in the central office needs routine maintenance, this worksheet will help to simplify the process.
Worksheet C outlines a step-by-step leak locating procedure and provides a record keeping area. Side one is designed essentially the same as Worksheets B, D and E. There is a logical layout of utility holes (indicated by alphabetized boxes) and a specially designated box which represents the office distribution panel.
Worksheet D—Leak Locating in Dual Feed Cables
This worksheet should be used when you are dispatched on a dual feed cable with low pressure. The worksheet outlines a procedure for locating the cause of the low cable pressure. It also serves as a record keeping device for future review, questions or similar problems at the same location. Leak locating with Worksheet D begins at the midpoint pressure transducer (designated as Utility Hole H on the worksheet).
Side one of Worksheet D provides areas to record the following information:
- Delivery pressure and cable pressure
- Utility hole numbers and locations
- Footages between utility holes
- Pneumatic resistance of cable
- Air Flow Calculations and Zero Leak Projections
- Cable structure (splice closures, interlacing, etc.)
Worksheet E—Leak Locating in Single Feed Cables
Worksheet E is used when prioritized dispatching points to a single feed cable with low cable pressure. It provides a logical, procedural approach to identifying the cause of the high flowing cable. It also serves as a record keeping device for future review, questions, or similar problems at the same location.
Side one of Worksheet E provides a location-by-location representation of the cable route from the point where a cable becomes a single feed lateral. The beginning of the lateral cable is represented by Location F. Twelve additional boxes are provided to record information at each associated location. Side two of Worksheet E consists of the specific procedures for locating a leak in a single feed system. It also provides space to record the task number, cable ticket information, and cause of the problem. Like the other worksheets, side two also lists the equipment and formulas required to perform the leak locating procedures.
Note: Worksheet E should be used in conjunction with Worksheet C when leak locating in offices with single feed systems.
Worksheet F—Leak Locating on Trunk and Toll Cables
This worksheet is used on trunk and toll cables to calculate pressure drop per foot and quickly identify the section of the cable with the leak. When used properly, it will enable you to eliminate large sections of cable and concentrate on a specific portion of the cable. Once this reduced area of search has been determined, you can use conventional leak locating tools such as the ultrasonic leak locator and/or gas detectors to identify the leak.
Worksheet F is used primarily on trunk and toll cable, or any cable where pneumatic resistance is constant and there is no interlacing. If a cable changes size or gauge, the pressure drop per foot procedures explained on the worksheet will be inaccurate.
Side one of Worksheet F is used to record cable pressure at each utility hole visited, pole/utility hole numbers and locations, footages between readings, and the pressure drop per foot between each location. Side two consists of the specific procedures for locating a leak in trunk and toll cables. It also provides space to record the task number, cable ticket information, and the cause of the problem..
Worksheet G—Reading Flows at the Flow Bank
Worksheet G is used exclusively in the Flow Bank System, for both routine and alarm leak locating. When used to list pressure and flow readings, the worksheet provides an ongoing record of the system's status. The worksheet is used to record flow readings for each cable at all Flow Bank locations. Flow Bank pressure is also recorded, as well as the direction of the flow for each cable-either towards the Flow Bank or towards the cable.
When all flows are recorded for each Flow Bank location, technicians can prioritize the flows, from highest to lowest, and begin routine leak locating on the cables to locate and fix the biggest leaks first.
Side one of Worksheet G is used to record the utility hole number, Flow Bank pressure, cable number, and flow reading. Side two lists the procedure for reading Flow Bank pressure and cable flows. It also provides space to record the task number and cable ticket information. Side two includes a Review Checklist, the equipment required for obtaining readings, and a place to record the total flow of all the Flow Banks.
