Conductivity TDS

It is now known that dark- and photoconductivity is connected with the structure of organic compounds 10>. The conductivity of organic dyes and other organic compounds, like that of inorganic semiconductors, is attributable to electronic charge carriers, i.e. electrons and positive holes. The dark conductivity [Pg.87]

Co-Polyphthalo-cyanine [sample No] H202-Decomposi- tion 50 [min] Conductivity [Pg.115]

Are pumps and day tanks installed for dosing the chemical inhibitors Are they interlinked with the conductivity/TDS control If not, is there a drip-feed system. 

Figure 7.25 The Enterprise 470 conductivity/TDS meter (Photograph courtesy of Barlworld Scientific-jenway).

Where c, and are the concentrations of chloroform or monochloroacetic acid in the permeate, in the feed and the base concentration of the de-ionized (DI) water, respectively. Chloroform concentrations were determined using a total organic carbon (TOC) analyzer using the UV-persulfate method (Phoenix 8000, Rosemount Analytical Inc., Tekmar Dohrmann Division, Santa Clara, CA). Concentration of monochloroacetic acid was determined using a conductivity/TDS meter with RS232C (CON 110 series, Oakton Instruments, Vernon Hills, IL, manufactured by Eutech Instruments, Singapore). 

One of the main aspects of US NDT TD activity is organising conferences, seminars, exhibitions and meetings of experts, conducting the leading European companies seminars in Ukraine. 

For a quick estimate of total dissolved solids (TDS) in water one can run a conductivity measurement. The unit for the measurement is mhos/cm. An mho is the reciprocal of an ohm. The mho has been renamed the Sieman (S) by the International Standard Organization. Both mhos/cm and S/cm are accepted as correct terms. In water supplies (surface, well, etc.) conductivity will run about 10 S/cm or 1 iS/cm. 

However, the local water supplier will often supply TDS and conductivity so you can derive the con ect factor for an area. 

TDS Total Dissolved Solids is commonly estimated from the electrical conductivity... 

Room design conducted heat gain (design gain) x actual TD... 

Another method of estimating TDS is to measure the electrical conductivity of the water, which is usually reported as pho or pS . This figure is roughly double the TDS in mg/1 as CaC03. 

The raw water silica is 22mg/l as Si02, and therefore becomes a major constituent of the treated water. Silica scale must now be avoided by raising the boiler water pH and letting silica rather than the TDS control the necessary blowdown. Silica scale not only has a tenth of the heat conductivity of calcium carbonate scale but it is glassy, adherent, and extremely resistant to boilercleaning chemicals. 

In practice, control over BW TDS more usually is provided by placing limits on electrical conductivity. 

Steam purity indicates the degree of inadvertent BW carryover, typically reflected by an increase in electrical conductivity from sodium and other ions present in the BW TDS. Iron and silica may also carry over, and the silica may be in a volatile form. Steam purity also is affected by the use of neutralizing amines (as an intentional measure). 

Demineralization by SAC(H)/WBA(OH) Removes virtually all TDS except silica and carbon dioxide. The weakly basic anion cuts operating costs through a significantly enhanced capacity and reduced regeneration demands. However any sodium slip from the cation unit passes through the anion and increases the conductivity of the treated water. 

Demineralization by SAC(H)/SBA(OH) Removes virtually all TDS, including carbon dioxide and silica. The TDS in treated water is normally below 2 to 4 ppm. Conductivity is below 10 to 15 pS/cm, but this depends on the degree of sodium slip from the cation. Any slip is converted to sodium hydroxide in the anion unit (salt splitting), causing a sharp increase in conductivity and increased silica solubility. The lack of a degasser drains the anion unit capacity and requires increased caustic for regeneration. 

Demineralization by SAC(H)/Degassing/SBA(OH)/MB Removes all TDS, including carbon dioxide and silica. This is a standard process where the RW is high in alkalinity and silica. The MB acts as a polisher with infrequent regeneration. Silica and sodium are both reduced to below 0.02 ppm as CaC03. Conductivity is below 0.1 pS/cm. A schematic layout of this type of plant is shown in Figure 9.3c. 

When incoming TDS is initially high, the resins (in salt form) provide additional electrical conductivity, which aids ion movement across the membranes. 

The problem of color due to tannin can be annoying, although not insurmountable. For small, simple boiler plants, the presence of color is, in fact, a benefit, as the depth of color is more or less related to the inhibitor concentration and the BW conductivity and TDS levels. Where multiblended formulations are employed, if the color is within range, then other parameters are also likely to be acceptable. Also, electrical conductivity is unaffected by color, and tannins do not appreciably add to the measurable TDS of the BW. 

NOTE This chart assumes oxygen scavenger, polymer, and other necessary water chemistry controls are in place. If determining TDS via a conductivity meter, use an un-neutralized sample. 

Ensure a maximum total solids of 20 ppb TDS (or equivalent conductivity) for once-through and sub- and supercritical boilers, 2 ppm TDS for industrial boilers. 

Maximum M alkalinity and conductivity or TDS limits must be consistent with acceptable steam purity, as determined by steam purity tests. In many cases, alkalinity limitations, rather than conductivity, determine BD requirements. 

ABMA assumes TDS (ppm) is 50% of electrical conductivity (micromhos). It is assumed that tests are made on unneutralized samples. 

Although LV TDS guidelines propose <750 ppm micromhos, the LV conductivity proposed is <3000 ppm, which infers TDS = 25% of conductivity, rather than the norm of 50% for un-neutralized BW (N.B. the ratio is 65% for city water). 

Maximum values of specific conductance are often not achievable without exceeding maximum T alkalinity values, especially in boilers below 900 psig (6.21 MPa) with greater than 20.0% MU water whose alkalinity is >20% of TDS naturally or after pretreatment by lime-soda or sodium cycle ion exchange softening. Actual permissible conductance values to achieve any desired steam purity must be established for each case by careful steam purity measurements. The relationship between conductance and steam purity is affected by too many variables to allow its reduction to a simple list of tabulated values. 

With regard to TDS and conductivity, only one of these parameters must be measured. 

The maximum values for BW dissolved solids are based on fully softened FW in accordance with the table. If, for whatever reason, FW with a significant hardness must be used, then the TDS and conductivity level should be reduced to achieve the SS limit. 

A measure of ability of water to conduct an electric current and often related to TDS content of water. Typically, one pS/cm units of conductivity x 0.65 equals ppm TDS. 

As expected for a WWTP effluent, turbidity and E. coli are higher than the specific standards for industrial wastewater reuse included in the new Spanish Regulation of Regenerated Wastewater (RD 1620/2007). Other parameters, such as conductivity or TDS may result in too much high level considering some specific industrial uses of water [11]. Therefore further treatment of the WWTP effluent is needed before reuse. 

Table 4 summarizes the efficiency of membrane filtration as preliminary treatment in the hybrid process to obtain regenerated water for industrial reuse. Working with the adequate cleaning cycle to avoid fouling and to keep a constant flux (10 1 min ) important reduction in suspended solids (90%) and turbidity (60%) of the wastewaters is achieved but there is no significant reduction of other chemical or physical parameters, e.g., conductivity, alkalinity or TDS, or inactivation of E. coli. 

Table 4 summarizes the efficiency of this hybrid MFAJV/NF process. Reduction of conductivity, turbidity, suspended solids and TDS was close to 100%. Conductivity values were reduced down to average values of 200 pS cm while turbidity and TDS reached 1.2 NTU and 102 mg 1 respectively. Thus, regenerated water could meet the standards for cooling and boiler feedwater [11]. 

Although certain variability in the quality of the WWTP effluent was found, regenerated wastewater by the selected process resulted of a good constant composition in the measured parameters, with important reduction of all the measured pollutants. Disinfection by UV achieved almost 100% of effectiveness in the destruction of microorganisms ( . coll). Conductivity, turbidity or TDS parameters... 

Table 6 shows the efficiency of the RO unit. 99.9% salt retention is reached additionally reduction efficiencies of 99% for TDS, silica and conductivity, 95% for... 

The effect of water salinity on crop growth is largely of osmotic nature. Osmotic pressure is related to the total salt concentration rather than the concentration of individual ionic elements. Salinity is commonly expressed as the electric conductivity of the irrigation water. Salt concentration can be determined by Total Dissolved Solids (TDS) or by Electrical Conductivity (EC). Under a water scarcity condition, salt tolerance of agricultural crops will be the primordial parameter when the quality of irrigation water is implicated for the integrated water resources management [10]. 

However, even with the most advanced measuring and simulation tools, the most efficient methods are simple calculations that give an order-of-magnitude estimation of the influence of a phenomenon. Time constants for diffusion, heat conduction, and acceleration are very useful. For example, the time constant for diffusion Td = f/D is the time it takes to fill a cube of size I by diffusion, and the time for a particle to accelerate from zero velocity to approximately two-third of the velocity of the surrounding fluids is 118/j, where p[Pg.331]

If the process is conducted reversibly, dQ = TdS where S is the entropy of the elastic body. Substitution of this expression for dQ in Eq. (5) will require dW to represent the element of reversible work. In order to comply with this requirement, the coefficients P and / in Eq. (6) must be assigned their equilibrium values. In particular, / will henceforth represent the equilibrium tension for a given state of the system, which may be specified variously by aS, F, and L, by T, F, and L, or by T, P, and L. Then... 

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