What is this blog post about?
Dear readers, this blog post covers the specification for variable flow type air-permeability apparatus (Blaine Type) which is covered in Indian Standard code book IS 5516 (1996). This standard covers the requirements of Blaine air-permeability apparatus its accessories used for determination of specific surface of cements, pozzolanas and other powdery materials.
A short Overview on Blaine’s Air-Permeability Test
Blaine air permeability test is performed to determine the fineness of cement by measuring the specific surface area of fine materials in cm²/g of test sample. Tap here to read the full procedure. (It covers definitions, apparatus list, IS code, test procedure, calculation sheet, formula and expression of result.)
Specifications for Blaine Air Permeability Apparatus | IS 5516
Now, read the Specifications of Blaine air-permeability apparatus and its accessories used for determination of specific surface of cements, pozzolanas and other powdery materials.
IS Code for Blaine Type Air-Permeability Apparatus
IS 5516: 1996 is the IS code for requirements of Blame type air-permeability apparatus and its accessories.
Blaine Type Air-Permeability Apparatus: Working Principle
The variable flow type or Blaine type air-permeability apparatus shall consist essentially of a means for drawing a definite quantity of air under a falling pressure head through a prepared bed of powder of a definite porosity. The number and size of the pores in a prepared bed of cement of definite porosity is a function of the size of the particles and determine the rate of air flow through the bed.
Blaine Type Air-Permeability Apparatus: Parts And Accessories
Permeability Cell, Perforated Disc, Plunger, Filter Paper Discs and Manometer are the main parts of Blaine type air-permeability apparatus and filter paper disc cutter and air evacuating rubber bulb are accessories. The detailed information has been covered in the next paragraphs.
Blaine Air Permeability Apparatus Diagram
A. Permeability Cell
- The permeability cell shall consist of a rigid right cylinder (12.7 ± 0.1) mm inside diameter A, constructed of austenitic stainless steel or other abrasion-resisting, non-corroding metal.
- The top and bottom faces of the cell shall be flat and normal to the axis of the cylinder, as shall the upper surface of the ledge at the bottom of the cell.
- The bottom of the cell shall form an airtight connection with the top of the manometer.
- The internal walls of the cell shall be smooth, true and vertical with a finish of 0.8 micron.
- A ledge 0.8±0.2 mm in width shall be an integral part of the cell located at a depth shown in Fig. 1 (Dimensions of Air-Permeability Apparatus) to support the perforated disc.
- The top of the permeability cell shall be fitted with a protruding collar to facilitate the removal of the cell from the manometer.
- The bottom end of the cell shall be flared downwards from the ledge portion to a length of 35±1 mm, along the axis if the cell is of the female type or if male type, the wall of the cell be flared upwards from the ledge level to a distance of 45±1 mm.
- The flaring shall be about 5° from the axis of the cell.
- The flaring either of the male type or female type shall ensure an airtight connection with the corresponding part of the manometer limb.
B. Perforated Disc
The disc shall be constructed of non-corrodible metal (preferably brass or austenitic stainless steel) and shall be 0.9±0.1 mm in thickness and perforated with 30 to 40 circular holes. Each one millimetre in diameter equally distributed over its area and finished smooth. The disc shall be of diameter A-0.1 mm and shall fit the inside of the cell snugly and get support on the ledge. The centre portion of one side of the disc should be marked or inscribed in a legible manner so as to permit the operator always to place that side downwards while inserting it into the cell. The marking or inscription shall not extend into any of the holes nor touch their peripheries nor extend that area of the disc that rests on the cell edge. When in position on the ledge in the cell, its plane surfaces shall be normal to the axis-of the cell.
C. Plunger
The plunger shall be constructed of the same material as the cell and shall fit into the cell with a clearance of not more than 0.1 mm. The bottom of the plunger shall sharply meet the lateral surfaces and shall be at right angles to the axis. An air vent shall be provided on one side of the plun er by flattening 3 mm. The top of the plunger shall be provided with a collar such that when the plunger is placed in the cell and the collar brought in contact with the top of the cell, the distance between the bottom of the plunger and the top surface of the perforated disc shall be 15.0±1 mm.
A plunger shall only be used with the corresponding cell the dimensions of which match within the permitted tolerances.
D. Filter Paper Discs
The filter paper shall be of medium porosity (Mean pore diameter 7 micron corresponding to No. 40 Whatman). The filter paper discs shall be circular, with smooth edges adopted to the dimensions of the cell.
Note:- Filter paper discs that are too small may leave part of the sample adhering to the inner wall of the cell above the top disc. When too large in diameter, the disc may have a tendency to buckle and cause erratic results.
E. Manometer
The U-tube manometer shall be constructed according to the design indicated in Fig. 1 (Dimensions of Air-Permeability Apparatus) using 9.0±0.4 mm outside diameter borosilicate glass tubing. One arm of the manometer shall be provided at the top with a conical socket to form an airtight fit with the conical surface of the cell. The same arm shall also have four etched lines and a T-joint whose positions shall have the dimensions shown in Fig. 1 (Dimensions of Air-Permeability Apparatus). The side branch of the T-joint shall lead to use airtight stopcock at a distance not more than 50 mm from the manometer arm and beyond which shall be attached a suitable aspiration device such as the rubber tube and bulb shown in Fig. 1 (Dimensions of Air-Permeability Apparatus).
The manometer shall be mounted firmly on the vertical board of the manometer stand, made of wood or suitable wood substitute or pressed steel sheet, in such a manner that the arms are vertical.
The manometer shall be filled to the level of the lowest etched line with a non-volatile, non-hygroscopic liquid of low viscosity and density, such as dibutylphthalate (dibutyl 1, 2-benzene-dicarboxylate) or light grade mineral oil.
F. Accessories
The filter paper disc cutter and air evacuating rubber bulb may be supplied as accessories.
Marking on Blaine’s Air Permeability Apparatus
The following information shall be clearly and indelibly marked on the apparatus in such a manner that it does not interfere with the performance of the apparatus:
- Identification of the source of manufacture,
- Date of manufacture,
- Serial number/Batch number, and
- Standard mark (BIS certification mark).
Blaine Apparatus liquid Name
Dibutylphthalate (Dibutyl 1, 2-benzene-dicarboxylate).
The Manometer of Blaine Air-Permeability Apparatus is filled to the level of the lowest etched line with a non-volatile, non-hygroscopic liquid of low viscosity and density, such as dibutylphthalate (dibutyl 1, 2-benzene-dicarboxylate) or light grade mineral oil.
FAQs
What is Blaine unit of cement?
The Blaine Air-Permeability Apparatus is used in measuring the fineness of Portland cement in terms of the specific area of cement expressed as total surface area in cm²/g.
What is air permeability apparatus used for?
Blaine Air Permeability Apparatus is used for the determination of fineness of cement by measuring the specific surface area of fine materials in cm²/g of test sample.
What is the price of Blaine apparatus?
The price of Blaine Air Permeability Apparatus for laboratory tests is Rs 13,400 in India. Tap here to buy.
What is the principle of air permeability?
Air permeability of a material is the measure of how easily air can pass through a material.
