Operating of Laminar flow Hood

Switch on UV light for 30 min with breakup interval for  10 min then Switch on blower for 15 min before transfers of micropropogation.

 Check to make sure that no paper or other object block the air intake at the bottom of the unit and that the sterile air coming out of the filter flows uniformly in the hood.

 Use 95% ethanol to wipe the working surface of the hood to remove the foreign bodies.

 Place only sterile glassware, appliances and culture tube or bottles inside the hood.

 During flame sterilisation of the glassware keep spirit lamp or Bunsen burner at a safe distance from the bottle containing alcohol to avoid fire.

 After using the hood, rewipe its surface with ethanol, remove all appliances, dishes, or bottles, and switch off the light and blower motor. Cover the hood with an air light screen.

@ Mohd,

I think you already have good answers to your own question (above).

In addition to what you had mentioned, the 'filter' of the hood needs to be changed and air flow quality needs to be checked by a certified company periodically. Besides, personal good practice of plant tissue culturing skill is also important. At the same time, teach and keep an eye on other people (or student helpers) who share the same hood with you.

Do you want to know the principle of Laminar flow function or do you want to know how to use laminar flow? The answer above answers the second question. The principle of laminar flow is cleaning air through a two stage filtration (prefilter which filters larger particulate matter like dust particles and the second one is called HEPA i,.e High Efficiency Particulate Air filter) with a pore size of ~0.2 micron. The air is forced through the filter by a blower. The filtered air thus is almost free of free of microbes and particulate matter. The air flows in layers, like sheets, hence   called laminar air flow cabinet . 

Linear Fracture Flow Analysis

Linear fracture flow is one of the flow regimes that can exist when a well has been hydraulically fractured. The purpose of analyzing linear fracture flow data is to determine the fracture half-length (Xf).

Constant Rate Solution

For oil and water:

image523.gif

For gas:

image524.gif

Linear fracture flow data will form a straight line when placed on a semi-log plot of pressure versus a square root time function (p vs. sqrt(time function)) for a buildup as shown below.

image233.gif

The slope (m) of this line is used to calculate the product of the fracture half-length and the square root of permeability (Xf sqrt(k)) as follows:

For oil and water:

image745.gif

For gas:

image748.gif

The permeability can be obtained from the radial flow analysis or estimated from core data or other tests. Once permeability is determined, fracture half-length is found using the following equation:

image528.gif

Summary of Equations for Linear Fracture Flow (Field Units)

Flow Period

Fracture Half-Length * Square Root of Permeability (ft md0.5)

Oil

Drawdown

image32.gif

image744.gif

Buildup

image39.gif

image746.gif

Gas

Drawdown

image33.gif

image747.gif

Buildup

image40.gif

image749.gif

Other Required Equations (Field Units)

Skin

image533.gif

For infinite conductivity fractures, when kf is large (FCD > 20)

Derivative

The signature of linear fracture flow data on a derivative plot is a straight line with a slope of 1/2. The position of this line is used to calculate the product of fracture half-length and root permeability (Xf sqrt(k)). Note that the product of fracture half-length and root permeability increases as the position of this line moves to the right.

Starting with the constant rate solution (see above) the derivative with respect to the logarithm of square-root time is:

For oil and water:

image534.gif

For gas:

image535.gif

Taking the logarithm of both sides:

For oil and water:

image536.gif

For gas:

image537.gif

This result is linear with time and, as a result, the derivative of linear fracture flow data falls on a straight line with a slope equal to 1/2 on a log Dp versus log Dt plot as shown below.

image155.gif

Using any derivative point on this line, the product of fracture half-length and root permeability (Xf sqrt(k)). can be determined as follows:

For oil and water:

image754.gif

For gas:

image757.gif

Summary of Equations for Linear Fracture Flow Derivative Analysis (Field Units)

Flow Period

Fracture Half-Length * Root Permeability (ft md0.5)

Oil

Drawdown

image136.gif

image756.gif

Buildup

image137.gif

image755.gif

Gas

Drawdown

image138.gif

image759.gif

Buildup

image139.gif

image758.gif

Hi

can the same LAF be used for both animal and plant tissue culture. or their is risk of contamination.