Design Criteria
The following shall be the basic design criteria for a fire protection system.
i) Facilities should be designed on the basis that city fire water supply is not available close to the installation.
ii) Fire protection facilities shall be designed to fight two major fires simultaneously any where in the installation. Fire water requirements will be decided as per guidelines given in Annexure of OISD
Fire Water System
Water is an essential and the most important medium available for fire protection. Water is used for fire extinguishment, fire control, cooling of equipment and protection of equipment and personnel from heat radiation. For these purposes water is used in various forms such as straight jet, water fog, water curtain, water spray, deluge/ sprinkler, for foam making etc. The main components of the fire water system are fire water storage, fire water pumps and distribution piping network along with hydrants and monitors.
Design Basis
The fire water system in an installation shall be designed to meet the fire water flow requirement for fighting two fires simultaneously requiring largest water demand.
Fire Water Demand
Various areas which can be under fire shall be considered and fire water demand for each area shall be calculated based on design basis.
Consider different cases for example fire water rate of five different cases and calculate the flow rate of each cases, then the total design fire water rate is the sum of water rates for 2 major fires.
Additional Information in the user interface
Spray Options
The options page provides control over a number of modelling and calculation options for the Spray/Sprinkler module:
Pressure Model
There are two options for the Pressure Model; the user can select either Darcy equation or Hazen- Williams equation.
For water and foam solution systems Hazen-Williams equation must be used. For foam concentrate systems Darcy equation must be used.
Design Rules
The fire protection systems follow norms like
- NFPA
- NFPA 96
- FOC
- OLDFOC
These norms are in-built in the Spray/Sprinkler module.
Spray or Sprinkler mode
There are two modes provided in this module. In the spray mode, all the nozzles input will be open by default and in the sprinkler mode all the nozzles input will be closed by default.
Pipe Types
In the spray module all pipes in a network must be of a specified type. A pipe type will be associated with a pipe schedule, and this schedule must already exist before the pipe type can be created. An optional lining definition may be provided by specifying the material and the lining thickness.
NOTE: If no pipe type is defined then the pipe drawing tool on the toolbar is disabled and the status message ‘No Pipe Type’ appears in the status bar at the bottom of the screen. This status will disappear when a pipe type is defined and the pipe button will be enabled:
Creating a new pipe type
To create a new pipe type
- Select the New button
- Select the associated schedule from the drop-down list provided - a name and description is provided automatically
- Then the C-factor of the pipe schedule is provided. The C-factor value will be taken into when the Hazen Williams formula is selected for performing the calculation.
- Provide velocities for all those bores which are to be provided by the schedule, bores being marked as available or unavailable by selecting the bore in the bottom right-hand corner window and selecting the Use in design or Avoid in design button as appropriate (default is all valid bores are marked as available).
- Linings can also be provided from the drop-down list provided – the thickness of the lining has to be given.
- Select Apply to complete the creation of the pipe type
Editing an existing pipe type
1. Select the pipe type from the top left-hand window
2. Make any changes required to the pipe type parameters;
3. Select Apply to commit the changes.
Deleting a pipe type
1. Select the pipe type from the top left-hand window
2. Select the Delete button.
A pipe type cannot be deleted if it is in use.
LIBRARIES
Libraries are used for storing items which would be used several times in the same network or in different networks.
This library is associated with the data file and is opened when the data file is open. It can contain the following for the Spray/sprinkler module
1. Pipe schedules
2. Nozzles
3. Pumps (Co-efficient Known & Co-efficient unknown)
4. Linings
5. Deluge Valve
There is only one local user library. It has the file extension .SLF and replaces all of the separate library files from previous modules. Whilst a data file is open; entries can be added, deleted or edited using the Library Editor dialog. PIPENET VISION automatically saves the library file when the ‘Sunrise Data File’ or .SDF is stored. The Library file takes the name of the ‘Sunrise Data File’.
The schedules option provides the user to feed the user-defined pipe schedule. There are about 8 pipe schedules which are built-in the PIPENET VISION; apart from this the user can also define the pipe schedules.
To the left is a list of available schedules, both built-in and user-defined, selecting any item in this list displays the properties of the schedule on the right.
At the top right are three fields common to all library editors:
1. The name of the schedule as it appears in pop-up menus, the length of this name is limited to 20 characters
2. An optional longer description
3. The source of the schedule, which may be one of the following:
- Built-in schedule provided with the Spray/Sprinkler module. Built-in schedules cannot be edited
- Local user library - these items may be edited whilst a network is open
- System library - these items can only be edited when using the External System Library Editor.
Below these three fields, a field contains the roughness, and below that a grid showing the standard nominal sizes and the corresponding internal diameters. If the nominal diameter is "unset" then the corresponding nominal diameter is not included in the schedule.
Nominal diameters are greyed-out indicating that their value is fixed, however by scrolling down to the end of the grid 10 user-defined sizes are revealed, for these entries both the nominal and internal bores can be edited.
Roughness and diameters are displayed in the user specified units
Adding a new schedule
To add a new schedule select the New button in the bottom left-hand corner of the dialog, enter the desired values (if the Description field is left empty it will by default be the same as the schedule name). Then enter the roughness and diameters. Then select Apply button to accept the new schedule or the Cancel button to abort.
Editing an existing schedule
Select the schedule to be edited from the left-hand window, enter the desired changes and then select the Apply button to accept the changes.
Deleting an existing schedule
Select the schedule to be deleted in the left-hand window and then click the Delete button.
Nozzles
The nozzles in the PIPENET VISION corresponds to the spray or sprinkler nozzles. The nozzles are open to atmospheres. Nozzles attributes can be directly entered in the schematic or nozzles can be called from the library.
The nozzle library dialog can be accessed through the libraries menu.
To view a library nozzle, select the required nozzle from the left-hand window and its properties are displayed on the right-hand side. To delete a nozzle select the nozzle in the left-hand window and then select the Delete button. To add a new nozzle:
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http://www.cadfamily.com/html/Article/Introduction%20and%20Basic%20Principles-Part%20B_675_4.htm
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