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Sahara Air Products

Exhaust Purge Air Dryer

Our Quality Components

 

& Standard Features

 

Ensure Safety and Reliability

 

 

Wet compressed air enters the top of the dryer and is directed to the drying tower by one of two solenoid actuated, non-lubricated switching valves. At the outlet of the dryer, 7% of the dry air is directed into an electric heater and heated to 375°F. This hot, dry “purge air” becomes “super dry” as it expands to atmospheric pressure in the regenerating tower where it removes moisture from the saturated desiccant.

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Model EP Standard Features

 

Controlled Blowdown

(Model EP-490 and larger)

 

After switchover, a small blowdown valve opens to slowly and quietly depressurize the chamber to be regenerated. This prevents shocking or fluidization of the desiccant, which can produce unwanted dusting. This blowdown is monitored by a pressure switch in the control system. The large purge exhaust valve will not be opened until the set point of the pressure switch (10 psi) is reached. In addition to preventing desiccant damage, this interlock protects your entire air system, by preventing the purge exhaust valve from opening under pressure. This means that if a check valve or inlet switching valve has failed to close correctly, your entire air system will not be blown to atmosphere.

 

Reduced Noise Level

 

By utilizing a muffler on the blowdown, noise levels are kept to a minimum. Our dryer complies with OSHA standards regarding noise tolerance at <85 dBA.

 

Indicating Temperature Controller

 

Incoloy-sheathed heaters are derated and are directly monitored for over-temperature protection through an independent set of heater temperature controllers, as well as an additional protective thermostat located in the cold zone of the heater for low flow protection. This complete redundancy virtually eliminates the possibility of heater burn-out, or worse, heater fires.

 

Low Pressure Drop

 

Excess pressure drop costs money. We design our complete system to keep pressure drop low. We have calculated pressure drop on these dryers at <3 PSID.

 

Ease of Maintenance

 

We provide you with a unique feature on our dryer that can make a big difference in your maintenance people’s time down the road. When necessary, instead of welding both towers to the structural steel base, we weld one and BOLT the other tower, where necessary. Valve maintenance is made much simpler by being able to remove one tower.

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Model EP Standard Options

 

Sahara Dew Point Demand System

 

Sahara’s option for increased energy savings reduces operating costs by sensing the dew point of the outgoing compressed air, automatically reducing energy consumption to the minimum amount required. A direct-reading dew point indicator is also available, allowing you to monitor the exact outlet dew point more conveniently.

 

Steam Heater

 

  • TEMA rated
  • Bypassed during cooling cycle to minimize fatigue failures
  • Fixed or removable tube bundles available
  • Copper, admiralty, stainless available

 

Indicating Lights

 

Includes Right Tower Online and Left Tower Online.

 

Fail-to-Shift Alarm Light

 

Indication that malfunction has occurred preventing towers from shifting at proper time or dew point sequence.

 

Moisture Indicator

 

Visual indication of outlet air moisture content by means of color change media.

 

NEMA 4, 7, or 12 Electrical Construction

 

Coalescing Prefilter

 

For optimum performance of a Regenerative Dryer application, we recommend a prefilter upstream of the dryer to protect the desiccant bed from contamination by oil, entrained water, or other contaminants. For this duty, we offer a Sahara High Efficiency (HEF) Oil Coalescing Prefilter. This unit is constructed of carbon steel to ASME standards and is designed to filter oil to 1 PPM and dirt particles to 0.3 micron with a 100 PSIG differential collapse pressure.

 

Particulate Afterfilter

 

We recommend an afterfilter downstream of the dryer to eliminate the possibility of desiccant dust carryover into the air system. For this duty, we offer a Sahara Particulate (AF) Afterfilter. This unit is constructed of carbon steel to ASME standards and the cartridges are designed to filter particles to 1.0 micron.

 

Drain Trap

 

We recommend utilizing a drain trap on each coalescing prefilter.

 

Filter Mounting

 

Filters may be mounted on dryer skid for ease of installation.

 

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Quality Components

 

Switching Valves

 

  • Reliable 2-way
  • Non-lubricated
  • Rated bubble-tight shutoff
  • Fire safe
  • 3” and larger are high performance butterfly valves with stainless steel internals and reinforced teflon seat

 

Electrical

 

  • Standard electrical construction is NEMA 1
  • Other NEMA classes are available
  • UL approved industrial control panels are available

 

Electric Heater

 

  • Electric heaters are derated to a maximum of 14 watts per square inch density for longer life
  • Construction material in inconel
  • Power: 460 V / 60 Hz / 3 Phase
  • Heating elements are not in direct contact with the desiccant
  • Bypassed during cooling (Model EP-490 and larger)

 

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.

 

 

Integral Components Included

 

  • Controls for automatic operation
  • Copper tubing and tubing holders on all pilot air and instrument air lines
  • Separate pilot air filter with pressure gauge and block valve to protect dryer control system
  • Separate controlled blowdown to start regeneration with safety interlock
  • Pressure switch controls purge exhaust valve; prevents heater from being energized until tower is depressurized; prevents catastrophic air loss in the event of valve failure (Model EP-490 and larger)
  • Heater over-temperature alarm light
  • Depressurization mufflers
  • Dual set point indicating temperature controller which regulates heater, dual set point provides safety backup, indicates regeneration temperature
  • Thermostat located in cold zone which provides safety backup in case of low flow
  • Stainless steel desiccant retainers
  • Desiccant fill and drain ports
  • Full one hour cooling cycle to reduce temperature spikes at tower switchover
  • On/Off switch
  • Tower pressure and temperature gauges
  • Heater outlet temperature gauge
  • Heater enabled light
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