Teledyne API Ultrafine Particle Monitor - Model 651

Technical Description

The critical pressure ratio is found by dividing the absolute pressure downstream of the orifice PD, by the absolute pressure upstream of the orifice PU. This ratio must be below 0.528 for air.

Critical pressure = PD ≤ 0.528

PU

The following pressure values are displayed on the Status screen and can affect the Model 651 flow.

Pressure Value

Vacuum

Inlet Pressure

Nozzle Pressure

Description

The vacuum pressure The inlet pressure.

The differential pressure across the sensor flow orifice

Temperature Control

The temperatures of the conditioner, growth tube, and optics are nominally maintained at 20°C, 60°C, and 60°C, respectively, with specified ambient temperatures in the operating range of 10°C to 40°C. Temperatures are controlled through feedback circuits on the main electronics board and are displayed on the Status screen on the front-panel display.

Note: For ambient temperatures outside the instrument operating range, the instrument temperature performance may not be maintained. Moderate increases in conditioner temperature will raise D50 a small amount.

Vacuum Supply

The external vacuum supply must be sufficient to maintain the sample flow at 0.12 L/min along with the auxiliary and transports flows. The recommended supply is 4 SLPM at 400 mbar absolute pressure.

Inlet Pressure Measurement

With an adequate vacuum supply, the Model 651 can operate at inlet pressures in the range of 75 to 105 kPa. The inlet pressure is measured by an absolute pressure sensor and is equal to the barometric pressure if no inlet restriction is present.

07506C DCN6727

57

Page 59
Image 59
Teledyne 651 operation manual Temperature Control, Inlet Pressure Measurement