Choosing the Right General Air Compressor for Your Sprinkler System

Selecting an air compressor for a dry-pipe or pre-action sprinkler system is not based solely on capacity. You must also consider the system volume, installation constraints, maintenance requirements, and the type of configuration best suited to the application.

General Air Products offers several compressors designed for fire protection applications, including lubricated tank-mounted, oil-free tank-mounted, and oil-free column-mounted models. Understanding the differences between these options allows you to make a more informed choice based on the project’s requirements.

Why Compressor Selection Is Important

Dry-pipe and pre-action systems rely on compressed air to maintain monitoring pressure. The compressor must therefore be properly selected to reliably achieve and maintain this pressure, while meeting installation requirements and applicable criteria.

When comparing options, it is recommended to evaluate the following in particular:

• system capacity;
• filling performance;
• mounting method;
• maintenance requirements;
• required accessories, such as an air retention device.

Proper selection helps ensure that the equipment is better suited to the actual system conditions.

Option 1: LT Plus Series, oil-lubricated tank-mounted compressors

General Air’s LT Plus Series features single-phase, oil-lubricated, tank-mounted fire protection air compressors designed for dry-pipe and pre-action sprinkler systems. These units are designed to bring systems up to monitoring pressure within 30 minutes in accordance with NFPA 13, making them a suitable option when system capacity and fill time are important criteria.

Key Features of the LT Plus Series

The LT Plus Series includes, among other features:

• an ASME-certified industrial tank;
• an ASME-certified safety valve;
• an air-cooled single-cylinder pump;
• a fan-type flywheel;
• an integrated air filter;
• multi-voltage NEMA motors;
• compressor oil included;
• a UL-listed discharge pressure switch;
• a pressure switch pre-wired to the motor;
• a 30-inch stainless steel flexible hose;
• vibration-damping pads.

This combination of features provides a tank-mounted solution well-suited for fire protection applications.

When to Choose an LT Plus Compressor

This type of compressor may be suitable when the project requires:

• a tank-mounted solution for larger system volumes;
• a lubricated compressor;
• a configuration with an integrated tank;
• filling performance that meets project requirements.

Option 2: OLT50075AC, tank-mounted oil-free compressor

The OLT50075AC is another tank-mounted option in General Air’s OL Plus series. Unlike the LT Plus models, it is an oil-free compressor, which can be advantageous in projects where the goal is to reduce maintenance requirements while retaining a tank-mounted configuration.

Technical Specifications of the OLT50075AC

According to published data, this model has the following specifications:

• System capacity: 500 gallons
• Average airflow: 6.06 CFM
• Motor: 3/4 HP
• Phase: single-phase
• Available voltages: 115 V and 208–230 V

The unit is factory-set to:

• 30 psi when running
• 44 psi when stopped

Recommended accessories include:

• the AMD-1 air hold-open device;
• the motor starter.

When to Choose the OLT50075AC

This model may be a good choice when the project requires:

• an oil-free, tank-mounted configuration;
• a compact solution for moderate demand;
• an installation with a reservoir, but requiring less maintenance than an oil-lubricated model;
• a single-phase unit with standard pressure.

Option 3: OLR600100AC, oil-free column-mounted compressor

The OLR600100AC is also an oil-free model, but it stands out for its column-mounted configuration rather than a tank-mounted one. This design can be particularly advantageous when space is limited or when installation flexibility is a priority.

Technical Specifications of the OLR600100AC

Published specifications indicate:

• System capacity: 600 gallons
• Average flow rate: 7.28 CFM
• Motor: 1 HP
• Phase: single-phase
• Available voltages: 115 V and 208–230 V

This model is described as:

• fully automatic;
• virtually maintenance-free;
• designed for column, wall, or floor mounting.

The factory settings are as follows:

• 30 psi when running
• 44 psi when off

Recommended accessories also include:

• the AMD-1 air retention device;
• the motor starter.

When to Choose the OLR600100AC

The OLR600100AC can be a cost-effective option when the project requires:

• column-mounted, wall-mounted, or floor-mounted installation;
• an oil-free solution;
• a more compact footprint;
• a simplified maintenance approach.

Comparison of the Three Options

Although these three compressors are designed for fire protection applications, they address different needs.

Choose the LT Plus series if the project requires:

• a tank-mounted oil-lubricated compressor;
• multiple capacity options for different system volumes;
• a configuration with an integrated tank;
• a filling performance designed to reach the monitoring pressure in 30 minutes in accordance with NFPA 13.

Choose the OLT50075AC if the project requires:

• an oil-free tank-mounted compressor;
• a more compact solution with a tank;
• reduced maintenance requirements;
• a single-phase unit at standard pressure.

Choose the OLR600100AC if the project requires:

• an oil-free compressor mounted on a column;
• greater flexibility in installation options;
• a compact solution for tight spaces;
• an automatic, low-maintenance unit.

Do not overlook the requirement for an air retention device

The choice of compressor must also take into account the accessories required to ensure proper pressure regulation.

General Air states that all tank-mounted compressors require an air-maintenance device to regulate system pressure. Furthermore, according to NFPA 13, an air-holding device is required on every dry system, unless the compressor capacity is less than 5.5 cu. ft./min at 10 PSI.

For the OLT50075AC and OLR600100AC models , recommended accessories include:

• the AMD-1 Air Maintenance Device;
• the Motor Line Starter.

These components should be taken into account from the earliest stages of design and selection.

Conclusion

There is no single type of compressor suitable for all dry-pipe and preaction sprinkler systems. The right choice depends primarily on system requirements, available space, the desired mounting type, and maintenance expectations.

The General Air product line offers three distinct approaches:

• the LT Plus series for an oil-lubricated, tank-mounted solution;
• the OLT50075AC for an oil-free, tank-mounted solution;
• the OLR600100AC for an oil-free, column-mounted solution.

By carefully comparing the project’s requirements, it becomes easier to select a compressor suited to the required monitoring pressure and the long-term proper operation of the fire protection system.