Excessive Backpressure

While here the tail pipe has the right construction and orientation, it is unfortunately not equipped with a drain. Therefore dirt can accumulate and create excessive backpressure, and can enter the valve and damage the seat surface, causing valve leakage after operation. The size of the tail pipe at the connection is smaller than the valve outlet. This will provide excessive built-up backpressure. Again, these considerations must be taken into account when sizing the valve, as the valve may otherwise be undersized. ... 

Make sure gaskets do not, even partly, obstruct the inlet or outlet passage as when opening the valve, (gasket) pieces may be tom off and cause leakage. Obstructions in the oudet passage may cause excessive backpressure. 

Figure 14.11 Damaged glue lines due to excessive backpressure.

The downstream piping must be adequately sized to effectively handle this volume. An undersized condensate returnline results in a high flash-steam velocity, which may cause waterhammer (due to wave formation), hydrodynamic noise, premature erosion, and high backpressure. The latter condition reduces the available working differential pressure and, hence, the condensate removal capability of the steam trap. In fact, with some traps, excessive backpressure causes partial or full failure. 

CeU gasket failure Prevent excessive backpressure replace gasket. 

Excessive backpressure decreases the amount of pressure drop that should be available for filtration appreciably reducing cycle length. High backpressure may be avoided by the use of take-away pumps on the filter outlet. Care should be taken, however, to ensure that the take-away pump is not creating negative pressure on the outlet of the filter. 

If inlet lines are too small, friction losses in these lines reduce the effectiveness of the feed pump. If outlet lines are too small, the same friction losses create excessive backpressure. 

Excessive backpressure on vacuum system. This is caused by an obstruction in the noncondensible discharge pipe or the discharge pipe sealed too deeply in the hot well. The obstruction must be removed or the depth of the seal in the hot well reduced to correct the problem. 

Excessive Backpressure There can be several causes of excessive column backpressure, but before we start to troubleshoot them, it is worthwhile to verify that the pressure is indeed excessive. To do this, we can estimate what the pressure should be by using the Kozeny-Carman equation discussed in detail in Section 2.2.S. 

In this section we will cover three problem areas the occurrence of extra peaks in the chromatogram, the source of excessive backpressure, and the causes of baseline drift. All three subjects are not necessarily column problems, but can be caused by other components of the HPLC system. 

Purge detector. Install back pressure regulator after detector. Check the instmment manual, particularly for Rl detectors (excessive backpressure can cause the flow... 

Depending on the extent of the engine exhaust system, a booster fan may be required to preclude excessive backpressure on the engine. Where more than one cell is involved, one fan would probably serve multiple cells. Coutrols would need to be provided to hold the back pressure constant at the engine (Fig. 3.30). 

Once the module has been opened, the surface of the membrane, glue lines, and feed spacers should be inspected for damage and for scale and foulants. Damaged glue lines can mean excessive backpressure was applied to the membrane module. Figure 14.12 shows blisters where the glue line has been breached. Permeate back pressure must never exceed... 

Exhaust system (vacuum technology) A plumbing system that removes gases and vapors from the work area and is located downstream from the last vacuum pump. This portion of the vacuum system can contain scrubbers to remove undesirable gases and vapors. The exhaust system should not present excessive backpressure on the vacuum pumping system, particularly during startup. See also Scrubbers Backpressure. 

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