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4.1.2

Determining System Load and Customer Demand

Profile

Designing a satisfactory gas distribution system for a new customer installation, or modifying an existing installation, requires the propane marketer to understand the operating characteristics and demand of the gas appliances, the customer’s life style and the gas appliance operating profile

In this module you will learn to:(1) Identify fundamental considerations for designing vapor

distribution systems (2) Determine the customer appliance use profile (3) Identify possible gas appliance system design problems

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Read and comply with company-specific customer installation planning documents such as guidelines for supply container sizing, delivery routing, or standard operating procedures for vapor distribution systems.

Fundamentals in Designing Vapor Distribution Systems

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Proper vapor distribution system design must meet two fundamental requirements:

1. Propane storage containers must supply adequate volumes of fuel gas vapor under the reasonably anticipated operating conditions of the gas appliances.

2. Pressure regulators and distribution lines must be sized to meet the total gas appliance system load without fuel gas vapor pressure and volumes dropping below appliance manufacturer minimum input specifications with all appliances operating at full load demand.

Fundamentals in Designing Vapor Distribution Systems

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Fundamentals in Designing Vapor Distribution Systems

Figure 1. Components of a Vapor Distribution Systemand Fundamental Design Considerations

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NFPA Code Requirements

NFPA 54

2002

Requirements for gas piping system design are located in Chapter 5 of the 2002 edition of NFPA 54, National Fuel Gas Code.

5.4.2.1 The volume of gas to be provided shall be determined directly from the manufacturers’ input ratings of the gas appliances served.

5.4.2.2 The total connected hourly load shall be used as the basis for pipe sizing, assuming all equipment is operating at full capacity simultaneously.

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NFPA Code Requirements

5.4.4 The design pressure loss in any piping system under maximum probable flow conditions…. shall be such that the supply pressure at the appliances is greater than the minimum pressure required for proper appliance operation.

5.1.2 When additional gas appliances are connected to a gas piping system, the existing piping shall be checked to determine whether it has adequate capacity. If inadequate, the existing system shall be enlarged as required, or separate gas piping of adequate capacity shall be provided.

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Determining the Customer Appliance Use Profile

Figure 2a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 2a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 2a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 2b. Example of a Gas Customer Profile (Reverse Side)

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Determining the Customer Appliance Use Profile

Figure 2b. Example of a Gas Customer Profile (Reverse Side)

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Determining the Customer Appliance Use Profile

Figure 2b. Example of a Gas Customer Profile (Reverse Side)

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Determining the Customer Appliance Use Profile

Special system design requirements may include:

• Large gas appliance system demand

• Year-round use of both indoor and outdoor gas appliances

• Large family and group social functions in severely cold weather

• Customer desire for concealed propane supply containers

• High-altitude appliance operation

• Concealed piping or tubing runs, or kitchen equipment installed in island locations

• Critical service factors

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Determining the Customer Appliance Use Profile

Figure 3a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 3a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 3a. Example of a Gas Customer Profile (Front)

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Determining the Customer Appliance Use Profile

Figure 3b. Example of a Gas Customer Profile (Reverse Side)

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Possible Gas Appliance System Design Problems

Figure 4. Example of Installation Planning Checklist

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Time to See If You Got the Key Points of This Module…

• Complete the Review on page 8.

• See if you are ready for the Certification Exam by checking off the performance criteria on page 9.