Frequently Asked Questions
1. Where CCTV should be used?
Anywhere! Literally - not only as a security measure but can be used to monitor staff protection, staff management, shrinkage and criminal damage, process monitoring, really a wide application.
2. Should I use Overt or Covert?
This is normally a personal issue however overt (visual) cameras are more popular especially as they not only record but act as a deterrent also. Covert (hidden) are used for delicate situations whereby you have ongoing problems that cannot be dealt with during conventional business conduct. Both types of systems are extremely effective.
3. Should I use Color or Black and White?
Another personal issue - although there are some guidelines to be adhered to: Color does not work well in dark conditions unless you have superb lighting or use of Digital Cameras. Infra Red will not work with Color Cameras. Black and White Cameras are normally a higher specification and offer a far crisper picture. Black and White will work well at night with the aid of Infra Red or normal Halogen Lighting.
4. Which Lens do I use?
Great question - how long is a piece of string? There is a calculation for this.
a. There are many factors involved in choosing a suitable lens, as the
lens size increases the left to right field-of-view narrows and the
distance increases.
A variable focus 1.8mm ~ 3.6mm lens is ideal for monitoring hallways,
doorways, and average size rooms
A 5.0mm ~ 40mm lens has the ability to be used for monitoring hallways and
doorways and can be easily adjusted to monitor long driveways or areas
several hundred feet away.
Beware of many online lens calculators which produce inaccurate angle
measures for these focal lengths. Also, most 1/4" CCD cameras produce a
significantly narrower field of view with the same focal length lens.
Due to the physical nature of lens optics, the numbers listed below should be
considered accurate to within ± 3° and therefore a few feet / meters as well.
They are intended as approximate guidelines to help select the appropriate
lens, while each camera in fact has its own unique field of view with each
specific lens. In addition, C- and CS-mount lenses typically deliver a slightly
narrower field of view than our comparable board lenses.
Lenses wider than roughly 5mm produce "artificially" wider fields of view
than more telephoto lenses. In order to do so, the video image is slightly
curved at the edges of the screen. While this artificial distortion is nominal
for focal lengths between 4.3 and 3.6mm, curvature increases with wider
angle lenses.
Each size lens is available with a manual or auto-iris lens.
The manual-iris lens is more affordable but should only be used in indoor
applications where the light source remains constant
The auto-iris lens can be used for indoor areas with varying light conditions
as well as outdoor installations.
HELP ON HOW TO SELECT LENSES:
SELECT SIZE: if your camera has 1/3" imager size you can go for 1/3" or
1/2" lenses. If your camera has 1/2" imager size you can use 1/2" lenses.
SELECT MOUNT TYPE: in 90% of cases it will be CS, check your camera's
manual
SELECT FOCAL LENGTH: If camera is strictly indoors and light never changes
go for manual iris lenses
SELECT TYPE OF IRIS: if camera is for outdoors or light changes go for DC
iris lenses (camera must support DC iris lenses) or video auto iris lenses
Varifocal lens will give you flexibility in adjustable field of view.
5. What is DVR?
DRV or Digital Video Recording is a PC based system or embedded system that records your CCTV images digitally rather than on a VHS tape. This DVR system will replace your Monitor, your Multiplexer and your VCR and the camera images are stored on the hard disc on the PC.
6. What are the backup devices supported by the system?
Data backup devices include CD-RWs, DVD-RAMs, DVD-RWs, DATs, etc., any device
that Windows recognizes as a drive, and you can also backup on a network drive.
The data is only be viewed through the supplied Backup viewer. Data backup is also
possible on the Search program, where it can be saved in AVI format, making it
conveniently viewable through the Windows Media Player(by enabling "View-
Caption" from the menu, you can also conform information data
7. Why do I need NFPA 72 compliance?
NFPA 72 is a prescriptive standard that applies to Fire Alarm Systems. While the NFPA 72 standard makes no mention of gas detection, many clients are applying NFPA 72 standards and requirements to both fire and gas detection systems. There are several advantages to NFPA 72 certified systems that include:
Allows for the combining of both fire alarm and gas detection functions
into a single safety system
Ensures that local "authorities having jurisdiction" like fire marshals or
fire authorities have assurance that the system complies with the
applicable codes and standards
Allows the end-user to lower their insurance costs because they are
using a certified system
A NFPA 72 certified solution ensures that you are complying with the
best practices in the industry as drafted by the NFPA
General Monitors' HazardWatch offers a flexible fire and gas detection platform which is FM certified to comply with the NFPA 72 standards and requirements.
8. When should I use a PLC vs. a Controller-based solution?
The choice between a PLC and Controller-based system is primarily driven by the size of the application.
PLCs are best suited for medium to large size gas detection systems (25+ points of gas detection). For very large systems, PLCs have the advantage of scaling fairly inexpensively to accommodate large point counts. PLCs offer the added benefit of extensive connectivity options for communicating with other DCS or ESD systems.
Controller-based gas detection lends itself to small to medium sized systems very effectively. A controller-based gas detection system is relatively easy to implement, and does not require software programming tools. The hardwired nature of a controller-based solution makes it inherently simple to troubleshoot and support.
General Monitors has the most complete line of gas and flame controllers in the industry. We offer multiple channel gas controllers like the 610A and DC110, or single point gas controllers in our 02A series with MODBUS communication.
9. What is the difference between fail-safe operation and the supervision requirements of the fire codes and NFPA 72?
The underlying principle of fail-safe design assumes that a process or item of equipment can be designed to take the process to a safe status on equipment failure or power interruption. This approach requires that the switch to “safe state” be possible without power and that the “normal operating state” of the equipment utilize energized control circuits.
Almost all detection, extinguishing and notification circuits of a Fire Alarm system are not normally energized and are not “fail-safe”. In order to be sure these fire circuits are intact and ready for use when needed these circuits are “supervised”. Supervision is normally done using a small current or voltage passed through a field circuit device called an “end of line device”. This small current or voltage is continuously monitored to verify that the circuit is intact and ready for operation. Fire Alarm systems in many cases need to activate suppression or notification equipment in the event of a hazardous condition and these systems require power be available to do so. This is the primary arguments behind the NFPA 72 requirements associated with backup power systems and batteries.
10. Should I take addressable fire alarm communications in to process areas?
Addressable fire alarm communication devices can be used in process areas when the operating specifications of the devices are compatible with the electrical and environmental conditions found in these process areas.
Most commercial addressable fire alarm equipment are normally rated for operation in general purpose environments with ambient temperatures between 0 and 50°C. Most process area environments have operating temperature ranges outside the 0-50°C range. Many process area environments require devices suitable for Division 1 or Division 2 areas.
When using commercial addressable fire alarm equipment we normally recommend that the addressable equipment be located only in environmentally controlled areas such as crew quarters, control rooms, office areas. If devices to be connected to the addressable fire alarm system are to be located outside these environmentally controlled areas, we recommend the use of an addressable to conventional circuit converter to be installed inside the environmentally controlled area with a conventional circuit interface to the process area located device.
11. What is Building Management System?
Building management system {BMS} is one of the important components in constructing a green building. It ensures taht the building remains 'green', through its life.
BMS is basically a solution which is put into a facility toensure an environment that is safe, secure, comfortable and energy efficient.When properly integrated into a facility, BMS can result in the following benefits:Optimize energy consumption,Provide alarm systems so as to take corrective actions,Monitor and control indoor comfort condition.
A BMS minimizes energy consumption & maximises indoor comfort, making it a valuable tool for any sustainable design.
12. What are the benefits of Building Management System?