FBD Interview Questions

In this article, we will discuss the most commonly asked interview questions related to the fluid bed dryer which is used in pharmaceutical industries for tablet manufacturing.

If you want to prepare for more interview questions you must subscribe to our YouTube channel Pharmainform & watch a complete playlist of interview-related questions.

In this article, we will only discuss the interview questions related to the FBD or fluid bed dryer.

FBD Interview Questions


What Is FBD?

FBD is the abbreviation of fluid bed dryer which is used in pharmaceutical industries to dry the wet mass of granules or to remove the moisture content from the wet granules during the process of wet granulation.


What Are Other Names Of FBD?

The FBD is also known as

  • Fluid bed dryer 
  • Fluidised bed dryer.


What Are The Types Of Fluid Bed Dryers?

There are two types of FBD

  • Vertical FBD
  • Horizontal FBD

Vertical FBD are the most commonly used fluid bed dryers in pharma industries.


What Is The Purpose Of FBD?

The main function or purpose of a fluid bed dryer is to dry the wet granules.


What Is The Principle Of FBD?

The FBD or fluid bed dryer works on the principle of fluidization where air carrying capacity for granules is greater than the settling velocity of granules.


Why Is FBD Known As A Fluidised Bed Dryer?

FBD is known as a fluidized bed dryer because the product remains fluidized in the drying chamber due to High air pressure & less settling velocity.


What Are The Components Of A Fluid Bed Dryer?

The following are the main components of a fluid bed dryer,

  • Air Processing Unit
  • Inlet Air Duct
  • Outlet Air Duct
  • Air Gate
  • Plenum
  • Drying Chamber
  • Product Trolley
  • FBD Filter
  • Fan Motor(Exhaust System)
  • Product Charging system
  • Product discharging system
  • HMI & Control Panel 


What Are CPP Of FBD?

CPP is a critical process parameter. The critical process parameters of FBD are as follows

  • Inlet Air temperature
  • Outlet Air temperature
  • Product Temperature
  • Air flow volume 


What Is the MOC Of FBD?

All the direct product contact parts of the fluid bed dryer are made of stainless steel 316L.


What Is the Purpose Of Filters Used In FBD?

The filters are installed in the drying chamber of FBD which allows the escape of air but prevents product loss.


Types Of Filters Used In FBD?

Two types of filters are used in fluid bed dryers depending upon the model of FBD.

Some dryers have stainless steel filters & others have cloth filters.


Why Do We Use Finger Shape Cloth Filter In FBD?

The cloth filters used in FBD have finger shapes or have pockets which help to increase surface area to reduce the drying time.

Read Detailed Answer 


What Are Other Names Of Cloth Filter In FBD?

The Cloth filter used in FBD is also known as,

  • Candle Filter
  • Finger Bag Filter
  • Pocket Filter


How To Prevent Filter Choking In FBD?

The Fluid bed dryers which have stainless steel filters are equipped with a blowback system to ensure filter cleaning & prevent choking of filters during the drying process.

The dryers that have cloth filters use a shaking system to prevent filter bag choking.


Which Type Of Sensors Are Installed In Fluid Bed Dryers?

The following type of sensors are installed in fluid bed dryer 

  • Inlet air temperature monitoring sensor
  • Outlet Air temperature monitoring sensor
  • Product Temperature monitoring sensor 
  • Differential pressure monitoring sensor 
  • Product trolley interlocking sensor 


What Is BBD?

BBD is a broken bag detector which is installed in the return duct of FBD & detects the escape of powder due to rupturing of filters & shuts down the fluid bed dryer to prevent product loss.

Read Detailed Answer 


What Is SFM?

SFM is a solid flow monitor & it is also known as BBD which we discussed in the above question.


What Is The InProcess Test Of Drying?

LOD or loss on drying is the InProcess test which is performed during the product drying process.


Advantages Of FBD?

Following are some main benefits of a fluid bed dryer.

  • Uniform product drying.
  • High product load can be dried in less time.
  • Color migration or mottling defects are prevented.
  • Easy to wash & clean.


What Is Kevlar Rope In FBD?

Kevlar Rope is a strong heat heat-resistant rope that is used to hang the finger bag filter in the drying chamber of a fluid bed dryer. This rope is also used to shake the finger bag filter to prevent blockage.

Read Detailed Answer 


What Is a Dutch Woven Screen?

The mesh that is installed at the bottom of the FBD product trolley is known as the Dutch Woven Screen. It is woven in such a way that it allows air to pass & prevent product leakage.

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Pore Size Of FBD Mesh?

The pore size of fluid bed dryer mesh is usually 100 to 200 micrometers.


What Is Raking In FBD?

Raking is the manual activity that is performed by using spatula & gloved hands to break down the large lumps in the fluid bed dryer product trolley to ensure uniform lifting of the product.

Read Detailed Answer 


WIP for FBD?

WIP is a wash-in-place system which is installed with FBD for automatic washing of the fluid bed dryer.


Product Charging to FBD

A pneumatic transfer system is used to transfer the sieved wet granules from high shear wet mill to the fluid bed dryer.


Product Discharging From FBD Discharging of dried granules from the product trolley of fluid bed dryer to the co-mill or containers is done by a pneumatic transfer system.

Image Credit

Image Source – Google | Image By –Made In China 

Read More 

  1. Granulation Interview Questions
  2. QA Interview Questions 
  3. Working on fluid bed dryer.
  4. Critical Process Parameters Of FBD
  5. Application of tray dryers in pharmaceuticals.
  6. Cleanroom classification in pharmaceutical industries.