Top Loading Orifice Flow Calibrator

A convenient orifice flow rate transfer standard for in field calibration of flow in high volume air samplers.

Accurate flow measurement is fundamental to this method for accurate determination of the extent of pollution in the air. US EPA and other pollution control authorities recommend that an air sampler (particularly high volume sampler) should be calibrated at regular intervals in the field using a calibrated orifice flow rate transfer standard. The orifice transfer standard should be re-certified once every year. A set of five multi-hole resistance plates are used to change the flow through the orifice so that several points can be obtained for the air sampler calibration curve.

Top Loading Orifice Flow Calibrator

Top Loading Orifice Flow Calibrator

Available Models : PSI - TLOC1 , PSI – TLOC2

Range :

PSI - TLOC 1 500 to 2000 LPM
PSI - TLOC 2 250 to 2500 LPM with a resolution of 1


In field calibration of high volume air samplers.

Physical Design Highlights

The TLOC assembly is fabricated as per US EPA design. It consists of a base plate, cylindrical pipe, an orifice plate, gaskets and mounting accessories. The base plate matches the filter holder and can be fixed directly to it in place of the pressure plate. It has provision for introducing and holding in place one of the 5 resistance plates at a time.

The cylindrical pipe is mounted directly on top of the resistance plate. The transfer standard orifice is fixed on the top of the cylindrical pipe. A pressure tap below the orifice is provided on the cylindrical pipe. This tap is used to measure pressure across the orifice, which is a measure of flow. The cylindrical pipe also has a provision for accommodating a temperature sensor (for TLOC2).

Salient Features :

  • Designed as per EPA specification
  • Precision SS Orifice
  • Portable compact light weight Multi-function electronic unit
  • Digital display of : Flow for STP & operating conditions, Differential Pressure across orifice, Operating temperature

Specifications :

Orifice Assembly

Model →
Specification ↓
Base Plate size Suitable for 8” x 10” standard filter holder
Cylindrical housing With pressure tap nozzle With pressure tap nozzle & temperature sensor union
Orifice Plate Precision machined SS as per USEPA mounted on cylindrical housing
Resistance plates 5 plates – 1 each with 17, 13, 10, 7 & 5 holes for varying flows
Material of construction Aluminum with high quality finish
Dimensions & Weight Size - 33 x 24 x 19 Cms.
Weight- 2.7 Kg.

Manometer Assembly (PSI-TLOC1)

Functions Pressure measurement
Flow Range 500 to 2000 LPM
Flow Measurement Accuracy ±2% of Full Scale
Pressure Measurement Range 20 – 0 – 20 cm WC
Manometer Type U-tube glass
Scale Graduation Resolution 1 mm
Enclosure Aluminum with acrylic front
Calibration Report Provided with traceability to National standard
Dimensions & Weight Size-500 x 80 x 40 mm Weight.-0.9 Kg.

Electronic unit (PSI-TLOC2)

Functions ∆p Pressure measurement
Temperature measurement
Flow computation at operating conditions
Flow computation at STP
Operator interface
Flow Range 250 to 2500 LPM with a resolution of 1 LPM
Flow Measurement Accuracy ±2% of reading with multi point Linearization
Pressure Sensor Range 5oC to 50oC
Temperature range U-tube glass
Display 32 character Alphanumeric LCD
Operating keys 3
Operating Power supply 6 V - 4 x1.5 V Dry Cells
AC adaptor Optional
Cabinet High quality ABS
Calibration Report Provided with traceability to National standard
Dimensions & Weight 210 x 100 x 40 mm 0.5 kg


TLOC Base plate suitable for fixing to Envirotech Respirable Dust Sampler, Carrying Case made of ABS

Related Products :

  • Low Flow Digital Calibrator Model PSI-DFC-1L
  • Air Flow Calibrator Model PSI - AFC 1L, PSI- AFC 1M, PSI- AFC 1H
  • Digital Flow Meter Model PSI-DFM-1L, Model PSI-DFM-1M, Model PSI-DFM-1H
  • Digital Air Flow Calibration System Model PSI- DFCS-1L, PSI- DFCS-1M, PSI- DFCS-1H
  • Digital Orifice Flow Calibrator Model PSI – OFC1, Model PSI-OFC2, Model PSI-OFC3