Bettis Guide: Selection Guide for Filter Regulators Manuals & Guides

Selection Guide

Part Number: FR.1001, Rev. 0

Release: July 2015

Selection Guide for Filter Regulators (FR)

Selection Guide

Part Number: FR.1001, Rev. 0

Table of Contents

Section 1: Overview ................................................................. 1

1.1 Purpose ............................................................................................................................................1

1.2 Filter Regulators (FR) or Air Preparation Units ..................................................................1

Section 2: Typical Performance Characteristics ........................ 5

Table of Contents

July 2015

Section 3: Dehydrator, Molecular Sieve Desiccant .................... 6

Section 4: Regulators (R) or the Combination

Filter Regulators (FR) ............................................... 7

Section 5: Calculating the Size of a Regulator ...........................8

Table of Contents

II

Selection Guide

Part Number: FR.1001, Rev. 0

Section 1: Overview

Section 1: Overview

1.1 Purpose

This manual provides a guideline for Valve Operating System (VOS) engineering on selection
of the Filter Regulators.

1.2 Filter Regulators (FR) or Air Preparation Units

Filter Regulators (FR) or Air Preparation units are essential for installation/control systems,
therefore the correct functionality is very important.

It is observed that the size and the installation of valves, fittings and others in a
control systems are carefully engineered, but the Filter Regulators (FR) seldom
get the same importance even though this element is equally necessary for a good
functionality and service life duration of the installed Valve Operating System (VOS),
including the actuator.

July 2015

11Overview

Section 1: Overview

July 2015

1.2.1 The following standard schematic symbols are used for Filter Regulator (FR).

Table 1. Air Preparation Units Symbol Chart

Part Number: FR.1001, Rev. 0

Selection Guide

See Table 1:

Symbol Description

FILTER/SEPARATOR

with manual drain

FILTER/SEPARATOR

with automatic drain

OIL REMOVAL FILTER

(coalescing lter)

AUTOMATIC DRAIN

LUBRICATOR

with manual drain

AIR LINE PRESSURE REGULATOR

adjustable, relieving

AIR LINE PRESSURE REGULATOR

pilot controlled, relieving

FILTER/REGULATOR (PIGGYBACK)

Manual Drain Relieving (With Gauge)

FILTER/REGULATOR (PIGGYBACK)

Auto Drain Relieving

AIR LINE COMBO F-R-L SIMPLIFIED

22

Overview

Selection Guide

Part Number: FR.1001, Rev. 0

1.2.2 The choice of Filter Regulator (FR) depends on the following parameters:

Section 1: Overview

July 2015

a. Capacity (Cv value)

b. Inlet and outlet pressure

c. Materials used

d. Self-relieving

e. Ambient temperature

f. Filter size (mass size in microns)

g. Filter drain - manual or automatic or semi automatic

h. Pressure gauge

i. Bowl capacity with or without viewing window

1.2.3 Why are the above parameters so important?:

a. Too small or too big, if sized incorrectly, the actuator will not open or close

at the accepted time. Also, the bigger the Filter Regulator (FR), the higher
the price.

b. Determination of the flow rate of Filter Regulator (FR) is a key.

c. Making a suitable choice of the Filter Regulator (FR) to work for a specified

ambient conditions and operating pressures

(1)

.

d. Customer preference for relief valves; install a relief valve with at least equal

Cv of a Filter Regulator's (FR) Cv.

e. Filter Regulator (FR) selection based on expected flow requirements.

f. Depending on the control components and factory recommendations.

g. Service capacity related and expected debris amount.

h. Customer preference (specified Filter Regulator (FR)).

NOTE:

(1)

A customer preference (hardly specied in project specications in general) could decrease

the service life time of the Valve Operating System (VOS) if other parameters are not explained
to the customers in conjunction with other key parameters.

33Overview

Section 1: Overview

July 2015

1.2.4 Filtration

1. Compressed air must be dry to prevent ice buildup.

2. Maximum of 40 micron particle size in the air system is acceptable, but when in

3. Selection criteria of the filter:

Part Number: FR.1001, Rev. 0

Selection Guide

combination with the Positioners like DVC, 5 micron particle size is required and the
recommended lubrication content shall not exceed 1 PPM.
(source, Fisher_ FIELDVUE_ DVC6200)

a. Determine the maximum flow.

b. Determine the maximum allowable pressure drop at the maximum

flow rate.

— With reference to the flow chart below (the size and execution could be

different per project), choosing the drop at the maximum recommended
flow rate is to an allowable ΔP of 2 psi (0.14 bar) but not higher than
5 psi (0.35 bar).

NOTE:

The ner the lter, the lower the capacity and a higher total ΔP over the lter.

Figure 1 Performance Characteristics for 20 Micron Element

Pressure Drop

Air Flow - SCFM@100 psig *5 micron element

calculate a 10% less flow

Sources: Fisher and Arrow Filters

F300-01

F300-02

44

Overview

Selection Guide

Part Number: FR.1001, Rev. 0

Section 2: Typical Performance Characteristics

FLOW CHARACTERISTICS

OUTLET PRESSURE

Section 2: Typical Performance Characteristics

July 2015

AIR FLOW

OUTLET PRESSURE

FLOW CHARACTERISTICS

AIR FLOW

PRESSURE DROP - bar

PRESSURE DROP - psig

Typical Performance Characteristics

FLOW - SCFM

FLOW - dm3/s

Source: Norgren Filter regulators

55

Section 3: Dehydrator, Molecular Sieve Desiccant

July 2015

Part Number: FR.1001, Rev. 0

Selection Guide

Section 3: Dehydrator, Molecular Sieve Desiccant

This is mostly used in natural gas operated systems and installed at the high-pressure side,
that is before the Filter Regulator (FR).

This element is highly recommended to be installed in a gas-operated systems where the
customer cannot guarantee the purity of the gas in accordance to system specifications.

3.2.1 Some issue will arise, such as:

• Issues in effectively absorbing water and hydrogen sulfide (H2S)

• The dehydrator, molecular sieve must have a capacity that is higher than the Filter

Regulator (FR) or filter booster which is installed downstream.

NOTE:

The gas composition must be determined to be able to select the correct dehydrator and the
molecular sieve.

A gas chromatograph is the recommended instrument to determine the gas composition.

3.2.2 Advantages of installing a dehydrator, molecular sieve:

• Reduces the risk of hydrate formation

• Reduces the risk of power gas supply (freeze off)

Below is a typical schematic of a Power Gas Application.

Figure 2 Typical Schematic of a Power Gas Application

DESICCANT
DEHYDRATOR

SUPPLY

FIELD
CONNECTION

DRAIN

FILTER

REGULATOR

POWER
GAS

RELIEF
VALVE

AUTO MANUAL

SIGNAL
GAS

66

Dehydrator, Molecular Sieve Desiccant

Selection Guide

Part Number: FR.1001, Rev. 0

Section 4: Regulators (R) or the Combination Filter-Regulators (FR)

July 2015

Section 4: Regulators (R) or the Combination

Filter Regulators (FR)

Regulators (R) or the combination Filter Regulators (FR) are designed to provide a quick
response and an accurate pressure regulation downstream.

Steps to determine the size of a regulator (Regulators (R) or Filter Regulators (FR)), are the
same steps to be followed to determine the size of the Filters.

Key parameters to be considered while sizing the regulators (Regulators (R) or Filter
Regulators (FR)):

c. It could be used mostly in both applications of compressed air or natural

gas, but needs to be indicated while designing the control system.

d. Ambient temperature and maximum inlet pressure.

For example: ASCO Modulair 160, maximum inlet pressure at +23°C is

17.5 bar and +50°C at 12 bar.

e. See example flow chart in Figure 3 below and the different flow capacities

versus different upstream and downstream pressures.

NOTE:

The Cv (1/2” Cv 4.3) mentioned in Figure 3 could be misleading. This is a given ow at the ideal set
point upstream versus downstream pressures and a lter of 25 microns.

Figure 3 1/2 NPT Regulator Flow Curves

OUTLET PRESSURE, psi

Regulators (R) or the Combination Filter-Regulators (FR)

FLOW, SCFM

1/2" Cv 4.3

Source: Versa

7

Section 5: Calculating the Size of a Regulator

July 2015

Part Number: FR.1001, Rev. 0

Selection Guide

Section 5: Calculating the Size of a Regulator

Calculating the size of a regulator is as follows:

1. Determine the minimum operating pressure of the actuator and the resistance in
pneumatic circuit first. This is also known as the conductance (Cv values) of the
elements that will be installed between downstream of the regulator and
the actuator.

2. If the pressure loss over the control system plus the minimum actuator operating
pressure is determined (which is the pressure needed to generate the minimum
operating torque, inclusive the safety factor), the sum of both will be the output
pressure of the Filter Regulator (FR).

3. Determine the consumption of the actuator in open (clockwise model actuator)
or close (counterclockwise model actuator) to ensure that the capacity of the
Filter Regulator (FR) is sufficient. Ensure to bring the total consumption to the
amount per minute, that is the expected minimum operations of the actuator
within 60 seconds (equal to the SCFM or LPM).

Sample calculation:

1. G4020-SR3-CW (volume: 3277 cubic inch).

2. Actuator is sized with a minimum operating pressure of 60 psi (mostly specified as
actuator's minimum operating pressure) and customer air supply pressure is 100 psi.

3. Expected downstream pressure loss over the control components is 5 psi.

4. Operating speed is 15 seconds to open.

5. 10% less flow during operations within 60 seconds.

6. Ambient temperature -15°C to +60°C.

Solution:

a. Determine the CFM of the actuator

(1 cubic inch per second to cubic feet per minute = 0.0347)

b. 3277/15 = 218.47 cubic inch per second = 7.60 CFM

c. At 60 psi = (60+5 ) x 7.60 = 494 SCFM (or 29,460 SCFH)

at an average ambient temperature +68°F > + 20°C

d. The consumption of the actuator and the minimum operating pressure

is known. In general, the maximum pressure loss over the control system
is determined at 5 psi, hence, the Filter Regulator (FR) must be set on a
minimum downstream pressure of 65 psi.

e. The capacity of the Filter Regulator (FR) can be determined, this will bring

to a 1-1/2” high. Refer to Figure 4.

8

Calculating the Size of a Regulator

Selection Guide

e) The capacity of the FR can be determined; this will bring us to a 1 1/2” high see below

Example.
Note: ideal pressure drop over the FR is 2- max. 5 PSI (the lower the ΔP allowable the
quicker the filter needs to be serviced)

Part Number: FR.1001, Rev. 0

NOTE:

There are two dierent pressure drops:

1.) The set pressure of the regulator, that is the air supply pressure and the VOS pressure .

2.) The pressure drop caused by the contamination in the supply air.
Ideal pressure drop over the Filter Regulator (FR) is 2 psi to maximum 5 psi (the lower the ΔP allowable,
the quicker the lter needs to be serviced).

Figure 4 Relief and Flow Characteristics

Section 5: Calculating the Size of a Regulator

July 2015

P3NR

PRESSURE DROP - bar

PRESSURE DROP - psig

FLOW - SCFM

FLOW - dm3/s

Figure 5 Example of Flow Capacities with Different Inlet and Outlet Pressures

bar

G1 - G1-1/4 - G1-1/2

OUTLET PRESSURE

Source: Parker high ow FR

NOTE:

1. 494 SCFM > 13990 l/min.

2. Maximum lter mass size 30 microns

Calculating the Size of a Regulator

AIR FLOW (INLET PRESSURE 8 bar)

Source: ASCO Numatics FR

9

Section 5: Calculating the Size of a Regulator

July 2015

NOTE:

1. When sizing the Filter Regulator (FR) combination, two elements are to be considered:

the Regulator and the Filter. Regarding the eventual losses in the control system before
the actuator, it is determined that the acceptable losses between the Filter Regulator
(FR) and actuator must not be higher than 4 psi (maximum of 5 psi).

2. Refer to the recommendations for the air quality for the DVC or in general, for the digital

controllers to provide reasonable service life of these components. It is recommended
that if the controller does not have an internal lter, then install a small in-line lter of
5 to 10 microns in the controller supply line.

3. When the Filter Regulator (FR) becomes larger than 1/2”, consider the use of a Filter

Booster (which is a proportional valve) which allows for:

a. Smaller Filter Regulator (FR), only needed in the control line to the

Filter Booster.

b. Smaller Solenoid valve(s).

4. In case the customer has specied high content of a water in their air, or the natural gas

supply, a dehydrator or coalescing lters shall be considered.

Part Number: FR.1001, Rev. 0

Selection Guide

Conclusion: Information given above suggests that the Filter Regulator (FR) needs to receive

more importance when the engineer sizes the actuator control systems.

10

Calculating the Size of a Regulator

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