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System design and the various types of systems

PAGA systems offshore

The PAGA is an important safety system. This is the system that broadcasts general announcements essential messages and alarms in times of emergency. The system is easily underestimated; there are many components and other systems tied into this powerful system that makes it possible for you to play specific messages tailored for each emergency.

Understanding the design of a PAGA system can help you make better decisions when you seek to outfit your offshore asset. To make it easy for you, we have also gathered the full overview of what you need to consider before choosing your system:

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Designing a PAGA System

The complexity of the design of your PAGA
system depends on what you need it to do, and where you are installing the system. For example, if there are many sections or zones within your facilities, you would need more amplifier modules along with the necessary components like loudspeakers and beacons. With that in mind, we can build a simple block diagram showing the connections between the components and which zones they will be playing messages into. Consider whether the system should be fully redundant A and B system or more systems in a network will also be noted here.


paga diagram


Following on, it is also important to decide on the type of components needed. Usually, your facility will require certification or compliance to certain standards and internal company technical standards. This means that we have guidelines to follow. For example, a PAGA system planned for an offshore Oil & Gas platform will require ATEX and/Or IECEx components for safety purposes. Knowing how a PAGA system is designed, will enable you to make more informed decisions and ensure that your system is the best-suited for the environment in which your facility is located.

However, there are also other factors such as the ambient noise/sound and zoning of the equipment that you have to take into consideration. To decide on the layout of your speakers and how powerful they need to be, it is also recommended that you do a sound coverage study to ensure that your PAGA system works as intended in the environment. 

Speak to your telecommunications integration personnel or one of our Semco Maritime PAGA experts to assist with your PAGA system requirements/calculations from FEED to Implementation.

Differences between PAGA and PAVA System

Having a public address (PA) system is an essential in your installations to ensure that important messages are disseminated on air to everyone within the facility. However, with many naming conventions in the market, particularly PAGA and PAVA, it may get confusing to which system to choose for your specific asset.

Below here, we introduce the two systems and talk about their minor differences.

PAGA System

A Public Address and General Alarm (PAGA) system is a critical personnel safety system that broadcasts emergency messages throughout a facility. PAGA systems are usually linked to fire/gas detection systems and can be set to trigger any alarms when incidents occur.

General alarms are traditionally codified signals that relate to a specific event, allowing trained personnel to quickly identify the type of incident and react accordingly. For example, an alarm to signal the presence of fire would be the continuous ringing of the bell or other defined tones. As such, these systems are usually applied in protected areas where the facility is usually occupied by personnel who have been briefed or trained about the alarm signals.

PAVA System

In general, a PAVA system is used to play public address announcements, broadcast advertisements or background music. As with the PAGA, PAVA systems are usually linked to any fire detection systems so that they are able to play the emergency messages during an incident with low delays.

With voice alarms, the messages are usually in spoken word instead of codified sirens, these systems are typically applied in public buildings, where people who are not trained in the signals can still receive messages and instructions accurately during an incident.

In conclusion, it is more a mater about words as both PAGA and PAVA system are very much functionally the same, especially when PAGA systems are also able to transmit voice messages as they normally are. Since they might be built with different needs in mind, the hardware making up the system and core functionalities will have to be different to ensure that all relevant standards are met. For example, setting up a PAGA system for an offshore Oil & Gas platform will require careful consideration for Ex field equipment to be used or even the complete PAGA system could be required to be Ex certified e.g. as Exp or Exd.

As such, it’s recommended that you seek a telecommunications expert in your industry to find out more about what standards you have to comply to for your facility and that is where Semco Maritime have the knowledge and experience to assist you.

Common problems with PAGA system sound coverage

The PAGA is an important safety system required in all installations because it ensures important messages are relayed to occupants during an emergency. However, simply placing loudspeakers across the facility is insufficient to ensure that your messages can be clearly heard and understood. You will need to take note of certain sound principles and work them into your considerations to ensure high sound quality.

Below here find out how reverb and echo affect the clarity of messages being played through your loudspeakers.

Reverb and Echo

Reverb and echo are similar concepts, and they generally refer to the persistence of the sound even after the source has been stopped. Reverb is the superposition of multiple echoes that takes place in an enclosed space, and usually conflates with the sound that has not yet finished. Echo is quieter, distinct, and separate in time repetition of sound, resulting from its reflection on a hard surface back to the listener.

The problem with reverb and echo in your installation is that it muddles the sound from the loudspeakers. If the reverb is too heavy, singular words will sound blurry and become intelligible. Similarly, echoes will cause the earlier half of your message to bounce back to the listener as the latter half of the message is playing. In the end, the muddled messages will only serve to confuse occupants.

As such, depending on the ambient noise and reverb present in your facility, the layout and loudness of your loudspeakers will have to be well planned to ensure that your messages can still be clearly understood.

Sound Coverage Calculation/Studies

To ensure that your PAGA system can blast messages clearly for occupants to hear, you’ll need to place your loudspeakers correctly. How many to place, which direction should the loudspeakers be facing, and where to place them, are all important considerations to take note of when installing the system. This is where sound coverage studies come into play and final STIPA measurements are carried out to prove our calculations and the best sound coverage and sound quality as possible.

sound coverage

Usually done via simulations through computer software, a sound coverage study investigates surrounding ambient noise, reverberation effects from nearby structures, and calculate the speech intelligibility of the of a signal test fed through the system. The speech intelligibility can then be further optimized by a mix of increasing the volume, increasing the number of loudspeakers, or highlight areas where reverberant noise level can be physically controlled (by adding acoustically absorbent structures, for example).

In an offshore environment, the importance of calculations and doing sound studies cannot be emphasized enough. As you have to contest with the noise from the environment, having such calculations done will help you plan for the most efficient layout where your messages can be clearly heard while minimizing usage of extra equipment. If you would like us to help with your PAGA system layout and calculation for optimal field design, you can also contact us here or you could start by downloading our e-book.