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Sahara Air Products

Blower Purge Air Dryer

Our Quality Components

 

& Standard Features

 

Ensure Safety and Reliability

 

 

Pressure Switch Control

 

Safety and reliability are our most important concerns. All of our dryers are designed and fabricated to provide you with this assurance. Our blower purge dryers are a prime example of this fact. The purge exhaust valves, V3 and V4, are not controlled by a timer like most other dryer manufacturers. They are controlled by a pressure switch that measures the pressure in the regenerating tower as it depressurizes. Once the pressure has dropped to 10 PSIG, the pressure switch allows the purge exhaust valves to open and turns on the heater and blower. Competitive dryers typically allow their purge exhaust valves to open 30 seconds after depressurization. What if a valve fails or even if a valve leaks? Air takes the path of least resistance. With a competitive dryer, if a valve fails you could vent all of your compressed air to atmosphere. Downstream you have no air flow or air pressure. This can have catastrophic consequences. SAHARA prevents this with our exclusive pressure switch control. This design also minimizes bed velocity during depressurization and reduces noise.

 

Derated Heaters

 

Our electric heaters are derated to operate at 14 watts/sq. inch for longer life. This conservative watt density means that heater burnout rarely occurs. Additionally, the heater is manufactured using Inconel; an extremely high temperature material. Heater burnouts and hot spots are virtually eliminated by this conservative design.

 

Redundant Temperature Controls

 

Our heaters are controlled by a triple redundant control system. The primary temperature controls are temperature transmitters. One is located at the discharge of the heater and regulates the temperature of the regeneration air. The dual setpoint of this transmitter provides extra protection; if the temperature rises past the primary setpoint, the secondary setpoint turns the heater off before a problem can develop. If for any reason this controller should fail, or if the air flow from the blower is interrupted, a second heater transmitter is located at the inlet of the heater. This triple redundant heater control virtually guarantees optimum performance and safety.

 

Sahara’s BP design stresses safety and reliability, eliminating the possibility of heater burnout and, more importantly, safeguards against catastrophic heater fire by implementing backup systems.

 

The use of an external heater eliminates the problems associated with internal heat-reactivated dryers. The externally mounted heater is not in contact with the desiccant which increases the desiccant life. In addition, the inconel-sheathed heater is derated to 14 watts/sq. in., virtually eliminating the possibility of heater burnout.

 

The heater is controlled by a dual setpoint transmitter, with additional protection provided by a transmitter located in the heater’s cold zone.

 

There is a third temperature transmitter located in the purge exhaust to monitor bed regeneration temperature.

 

Low Pressure Drop

 

The complete system is designed to keep pressure drop low. The pressure drop is calculated at <3 PSID.

 

Controlled Blowdown

 

To prevent shocking or fluidization of the desiccant, separate depressurization and purge exhaust valves are used. Controlled depressurization occurs before opening the purge exhaust valve for regeneration.

 

Ease of Maintenance

 

Where necessary, when valves are mounted between towers, instead of welding both towers to the structural steel base, we weld one and BOLT the other tower. Valve maintenance is made much simpler by being able to remove one tower.

 

 

Our valves work, so you can relax.

Blower

 

Quiet and reliable centrifugal blower provides years of trouble-free service. This blower design allows us to meet the low dBA noise level specifications required in today’s environments without additional sound-proofing.

 

Switching Valves

 

Incredibly reliable 2-way, butterfly valves are high performance, non-lubricated. These valves are rated bubble tight shutoff and are even fire safe. 2" and smaller are 2-way rack and pinion actuated bronze ball valve. 3" and larger are high performance butterfly valves with stainless steel internals and reinforced teflon seat. All valves can be serviced in the field.

 

Electrical

 

Housed in a NEMA 1 enclosure and built to the latest NEC Guidelines.

 

PLC Control

 

The PLC control system is a programmable controller with a touch screen display. The PLC controls all operations of the dryer automatically, integrating with the optional Dew Point Demand System to provide the ultimate in user friendly controls. The DPDS indicates the exact outlet dew point of the dryer at all times and allows the dryer to shift towers on dew point, rather than time.

 

Optional Steam Heater

 

Instead of an electric heater, steam may be used to regenerate the desiccant. If 150 PSIG steam is available, a steam to air heat exchanger may be used to reduce the operating cost of the drying system. A SAHARA exclusive is a bypass of the heat exchanger during cooling to prevent thermal cycling of the heat exchanger.

 

 

Extended life and reliability;

more benefits from SAHARA.