PFD

Unit layout as installed is the next step of preparation. This may take some effort if analysts have not been involvea with the unit prior to the plant-performance analysis. The equipment in the plant should correspond to that shown on the PFDs and P IDs. Wmere differences are found, analysts must seek explanations. While a hne-by-line trace is not required, details of the equipment installation and condition must be understood. It is particularly useful to correlate the sample and measurement locations and the bypasses shown on the P IDs to those ac tuaUy piped in the unit. Gas vents and liquid (particularly water-phase) discharges may have been added to the unit based on operating experience out not shown on the P IDs. While these flows may ultimately be small within the context of plant-performance an ysis, they may have sufficient impact to alter conclusions regarding trace component flows, particularly those that have a tendency to build in a process. 

Process Flow Diagram (PFD) A diagram that shows the material flow from one piece of equipment to the other in a process. It usually provides information about the pressure, temperature, composition, and flow rate of the various streams, heat duties of exchangers, and other such information pertaining to understanding and conceptualizing the process. 

Discuss the main differences between a process flow diagram (PFD) and a process piping and instrument diagram (P ID). 

System description is tlie compilation of tlie process/plant information needed for tlie risk analysis. For e. ample, site locations, environs, weatlier data, process flow diagrams (PFDs), piping an instnmientation diagrams (P IDs), layout drawings, operating and maintenance procedures, technology documentation, process chemistry, and tliermophysical property data may be required. 

Table 5.2-1 Comparison of different phosphine ligands in the Rh-catalyzed hydroformylation of 1-octene in [BMIM][PFd.

Set the major reviews (PFDs, P IDS, etc.) early, as opposed to waiting until the basic design is completed. This will minimize the project s cost by lessening rework... 

PFBS, PFHxS, PFHpS, PFOS, PFDS, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA... 

PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTrA, PFTeA, PFHxDA, PFODA, PFBS, PFHxS, PFOS, PFDS, FOSA PLE (MeOH solvent) — Evaporation to 1 + 30 mL water - SPE by Oasis WAX LC-ESI-MS-MS (QqLIT) 50-2,772 pg/ga [91]... 

Before the HAZOP study is started, detailed information on the process must be available. This includes up-to-date process flow diagrams (PFDs), process and instrumentation diagrams (P IDs), detailed equipment specifications, materials of construction, and mass and energy balances. 

Adjust the failure frequency to include the probabilities of failure on demand (PFDs) for each independent layer of protection. 

The PFD for each independent protection layer (IPL) varies from 10"1 to 10"5 for a weak IPL and a strong IPL, respectively. The common practice is to use a PFD of 10"2 unless experience shows it to be higher or lower. Some PFDs recommended by CCPS (see footnote 6) for screening are given in Tables 11-4 and 11-5. There are three rules for classifying a specific system or action of an IPL ... 

Passive IPLs Comments (assuming an adequate design basis, inspections, and maintenance procedures) PFDs from industry1 PFDs from CCPS1... 

PFD,y is the probability of failure of the /th IPL that protects against the specific consequence and the specific initiating event i. The PFD is usually 10 2, as described previously. 

Table 11-5 PFDs for Active IPLs and Human Actions...

The frequency of a cooling water failure is taken from Table 11-3, that is, / = 1CT1. The PFDs are estimated from Tables 11-4 and 11-5. The human response PFD is 10"1 and the PFD for the BPCS is lO-1. The consequence frequency is found using Equation 11-30 ... 

The concept of PFD is also used when designing emergency shutdown systems called safety instrumented functions (SIFs). A SIF achieves low PFD figures by... 

SIL1 (PFD = 10-1 to 10 2) These SIFs are normally implemented with a single sensor, a single logic solver, a single final control element, and requires periodic proof testing. 

Determine the expected failure rates and MTBFs for control systems with SIL1, SIL2, and SIL3 ratings with PFDs of 10 2,10-3, and 10 4, respectively. 

Determine the MTBF for SIL1-3 systems, if they have PFDs of 10 1,10-2, and 10 3, respectively. (Note This is not the same as Problem 11-15.)... 

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