diff --git a/spec/pipe_flow/lechaptcalmon.spec.ts b/spec/pipe_flow/lechaptcalmon.spec.ts
index 125dac098aaadabab2a99f7eda196c10d8e8f4c5..4a76a80a21a2a5742ddd1d672cd913a42875bb50 100644
--- a/spec/pipe_flow/lechaptcalmon.spec.ts
+++ b/spec/pipe_flow/lechaptcalmon.spec.ts
@@ -1,12 +1,12 @@
 import { ParamCalculability } from "../../src/param/param-definition";
-import { LechaptCalmon } from "../../src/pipe_flow/lechaptcalmon";
-import { LechaptCalmonParams } from "../../src/pipe_flow/lechaptcalmon_params";
+import { PL_LechaptCalmon } from "../../src/pipe_flow/pl_lechaptcalmon";
+import { PL_LechaptCalmonParams } from "../../src/pipe_flow/pl_lechaptcalmon_params";
 import { SessionSettings } from "../../src/session_settings";
 import { MessageCode } from "../../src/util/message";
 
-function getLechapt(): LechaptCalmon {
-    const l = new LechaptCalmon(
-        new LechaptCalmonParams(
+function getLechapt(): PL_LechaptCalmon {
+    const l = new PL_LechaptCalmon(
+        new PL_LechaptCalmonParams(
             0.3, // débit
             0.5, // diamètre
             0.1, /// perte de charge
@@ -22,7 +22,7 @@ function getLechapt(): LechaptCalmon {
     return l;
 }
 
-let lechapt: LechaptCalmon = getLechapt();
+let lechapt: PL_LechaptCalmon = getLechapt();
 
 describe("Class LechaptCalmon : ", () => {
     beforeAll(() => {
diff --git a/src/index.ts b/src/index.ts
index 72a9c87d76af75b95855c64e09fd9293e48f57c1..8c33e4b681a0fb4b3e2a73bab6af83c29f8e76bc 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -60,7 +60,7 @@ export * from "./pab/pab_nombre_params";
 export * from "./pab/pab_puissance";
 export * from "./pab/pab_puissance_params";
 export * from "./pab/cloison_aval";
-export * from "./pipe_flow/lechaptcalmon";
+export * from "./pipe_flow/pl_lechaptcalmon";
 export * from "./lc-material";
 export * from "./structure/dever";
 export * from "./macrorugo/macrorugo";
diff --git a/src/pipe_flow/lechaptcalmon.ts b/src/pipe_flow/pl_lechaptcalmon.ts
similarity index 91%
rename from src/pipe_flow/lechaptcalmon.ts
rename to src/pipe_flow/pl_lechaptcalmon.ts
index b430f33356032193baaf9ced75dda5060ded599e..46f6f33d2d50028ef81178ff0499fa232d5fd31a 100644
--- a/src/pipe_flow/lechaptcalmon.ts
+++ b/src/pipe_flow/pl_lechaptcalmon.ts
@@ -5,12 +5,12 @@ import { ParamCalculability } from "../param/param-definition";
 import { Message, MessageCode } from "../util/message";
 import { Observer } from "../util/observer";
 import { Result } from "../util/result";
-import { LechaptCalmonParams } from "./lechaptcalmon_params";
+import { PL_LechaptCalmonParams } from "./pl_lechaptcalmon_params";
 
 /**
  * Calcul des pertes de charge dans un tube à partir des tables de Lechapt et Calmon
  */
-export class LechaptCalmon extends Nub implements Observer {
+export class PL_LechaptCalmon extends Nub implements Observer {
 
     private static _materials: { L: number, M: number, N: number, title: string }[] = [
         {
@@ -69,7 +69,7 @@ export class LechaptCalmon extends Nub implements Observer {
         }
     ];
 
-    constructor(prms: LechaptCalmonParams, dbg: boolean = false) {
+    constructor(prms: PL_LechaptCalmonParams, dbg: boolean = false) {
         super(prms, dbg);
         this.setCalculatorType(CalculatorType.LechaptCalmon);
         this._props.addObserver(this);
@@ -77,7 +77,7 @@ export class LechaptCalmon extends Nub implements Observer {
     }
 
     public static get materials() {
-        return LechaptCalmon._materials;
+        return PL_LechaptCalmon._materials;
     }
 
     public get material(): LCMaterial {
@@ -91,8 +91,8 @@ export class LechaptCalmon extends Nub implements Observer {
     /**
      * paramètres castés au bon type
      */
-    get prms(): LechaptCalmonParams {
-        return this._prms as LechaptCalmonParams;
+    get prms(): PL_LechaptCalmonParams {
+        return this._prms as PL_LechaptCalmonParams;
     }
 
     public Calc(sVarCalc: string, rInit?: number): Result {
@@ -161,7 +161,7 @@ export class LechaptCalmon extends Nub implements Observer {
     private applyMaterialPreset() {
         const m = this.properties.getPropValue("material");
         if (m > 0) {
-            const values = LechaptCalmon._materials[m - 1]; // "0" means no preset
+            const values = PL_LechaptCalmon._materials[m - 1]; // "0" means no preset
             this.prms.L.singleValue = values.L;
             this.prms.M.singleValue = values.M;
             this.prms.N.singleValue = values.N;
diff --git a/src/pipe_flow/lechaptcalmon_params.ts b/src/pipe_flow/pl_lechaptcalmon_params.ts
similarity index 97%
rename from src/pipe_flow/lechaptcalmon_params.ts
rename to src/pipe_flow/pl_lechaptcalmon_params.ts
index c10163a437cb466487b6ec219aeb1b1931f489e3..147183f3968fdf3bf1b9cf2b9bc9cbfe1a5bccf0 100644
--- a/src/pipe_flow/lechaptcalmon_params.ts
+++ b/src/pipe_flow/pl_lechaptcalmon_params.ts
@@ -5,7 +5,7 @@ import { ParamsEquation } from "../param/params-equation";
 /**
  * paramètres pour le calcul Lechapt et Calmon
  */
-export class LechaptCalmonParams extends ParamsEquation {
+export class PL_LechaptCalmonParams extends ParamsEquation {
     /** Débit */
     private _Q: ParamDefinition;
 
diff --git a/src/pipe_flow/pressureloss.ts b/src/pipe_flow/pressureloss.ts
new file mode 100644
index 0000000000000000000000000000000000000000..65b051d1b413109f37ea3f43661507a1a6b929ec
--- /dev/null
+++ b/src/pipe_flow/pressureloss.ts
@@ -0,0 +1,21 @@
+import { Nub } from "../nub";
+import { Observer } from "../util/observer";
+import { Result } from "../util/result";
+
+export class PressureLoss extends Nub implements Observer {
+
+    /**
+     * paramétrage de la calculabilité des paramètres
+     */
+    protected setParametersCalculability() {
+    }
+
+    public Equation(sVarCalc: string): Result {
+        return undefined;
+    }
+
+    // interface Observer
+
+    public update(sender: any, data: any) {
+    }
+}
diff --git a/src/session.ts b/src/session.ts
index 31f5cdcebdc95a30520eb6a7be7f72b0f8e24baf..0496e9ad0741d764b2a5f62a2eded5514c70e2f1 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -62,8 +62,8 @@ import { PabPuissance } from "./pab/pab_puissance";
 import { PabPuissanceParams } from "./pab/pab_puissance_params";
 import { ConduiteDistrib } from "./pipe_flow/cond_distri";
 import { ConduiteDistribParams } from "./pipe_flow/cond_distri_params";
-import { LechaptCalmon } from "./pipe_flow/lechaptcalmon";
-import { LechaptCalmonParams } from "./pipe_flow/lechaptcalmon_params";
+import { PL_LechaptCalmon } from "./pipe_flow/pl_lechaptcalmon";
+import { PL_LechaptCalmonParams } from "./pipe_flow/pl_lechaptcalmon_params";
 import { Solveur } from "./solveur/solveur";
 import { SolveurParams } from "./solveur/solveur_params";
 import { Dever } from "./structure/dever";
@@ -394,7 +394,7 @@ export class Session {
                 break;
 
             case CalculatorType.LechaptCalmon:
-                prms = new LechaptCalmonParams(
+                prms = new PL_LechaptCalmonParams(
                     3, // débit
                     1.2, // diamètre
                     0.6, /// perte de charge
@@ -405,7 +405,7 @@ export class Session {
                     0, // Ks Perte de charge singulière
                     nullParams
                 );
-                nub = new LechaptCalmon(prms, dbg);
+                nub = new PL_LechaptCalmon(prms, dbg);
                 break;
 
             case CalculatorType.SectionParametree: