Teledyne HFM-E-200 D =, 0.0014 Q, 0.0028 σ Q, HFC-E-202 Orifice, ΔΡ Ρ d, Where, Formula

Where:
	Formula 1:	Formula 2:
D =	0.0028σQ	D =	0.0014Q
	Pu		ΔΡ • Ρd
			σ

D = Diameter in inches

Q = Flow rate in standard liters per minute

P = Pu - Pd in PSI

Pu = Upstream pressure in PSIA

Pd = Downstream pressure in PSIA

σ= Specific gravity of gas

Choose the orifice form Section 5.0 that has the closes larger diameter to the calculated diameter.

4.7.1. HFC-E-202 Orifice

To change the orifice in the HFC-E-202 series, turn the instrument upside-down and turn the orifice counterclockwise with a 9/64” Allen wrench until it stops coming out. Then grasp the exposed orifice end and pull it straight out. See Figure 4.2.

Prior to reinstallation of the orifice, inspect the two O-rings mounted on it for damage. Replace if cut or gouged.

Lubricate the O-rings slightly with a silicone based grease, and the threads with anti-galling compound. Push the orifice into its hole and screw it in until it is flush with the instrument base. Apply pressure to the inlet side of the instrument.

Turn the Valve Override switch to CLOSE or unplug the instrument. Screw the orifice in a few more turns until the flow through the instrument stops, then turn it an additional 1/8 turn clockwise.

PARKER O-RING

#2-008 VITON

ORIFICE

(see P/L per P/#

Fig 4.2

HFM-E-200/HFC-E-202

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